My goodness, David. Your post was very long, which you acknowledged. Maybe too long, but I do appreciate your effort to be thorough about this. It's probably too much for most to take in with one post. But, I somehow had the patience and attention span to read it all (it wasn't easy, though!), but I'm not sure if many others will.
Since your post is so long, it will require a long response and I decided not to address every point that you made one by one because that would take forever. Instead, I will just give you my understanding of the "short time" of Revelation 12:12 and explain why I believe it is a different time period than the "little season" of Rev 6:11 and Rev 20:3. And, yes, I do equate the little season of Rev 6:11 with the "little season" of Rev 20:3 and I'll explain why in a bit.
We know that the New Testament was not written in English but rather in Greek, so there are times when it is necessary to dig deeper for understanding by looking at the Greek text. You don't have to be a Greek expert to do that. There are tools you can find online to help show you the Greek words and their definitions for each English word in an English translation.
Anyway, let's start with looking at the Greek words translated as "short time" in Rev 12:12 and "little season" in Rev 6:11 and Rev 20:3.
Revelation 12:12 Therefore rejoice, ye heavens, and ye that dwell in them. Woe to the inhabiters of the earth and of the sea! for the devil is come down unto you, having great wrath, because he knoweth that he hath but a short (Greek: oligos - Strong's G3641) time (Greek: kairos - Strong's G2540).
I have seen a number of people reference this verse who, like you, assume that this "short time" that Satan gets to try to take out his wrath on Christians after being kicked out of heaven is a literally short amount of time.
The Greek word translated as "short" there is oligos and that word can be used to refer to a relatively small number of a limited number rather than a literally small number. Here is the best example of that I could find:
Matthew 22:14 For many are called, but few (Greek: oligos) are chosen.
This is what Jesus said after telling the parable where he compared entering the kingdom of heaven (being saved) with being invited to a wedding banquet. The ones initially invited (the Jews) mostly rejected the invitation and then the invitation went out to the highways (Gentile nations) after that and many (a multitude) end up being invited.
So, what Jesus was saying there was that many are called/invited to salvation and few are chosen/saved. Therefore, we know that even though few are chosen the number of which are chosen/saved is actually a large number (many millions or however many it is). It's just relatively few compared to the overall "many" who are called.
So, with that in mind, I believe that the "short time" of Revelation 12:12 is only meant to be understood as a relatively short and limited amount of time. Satan knows that his time is limited and that Christ defeated Him and that he can't accuse believers before God in heaven anymore, and he is aware of what Revelation 20:10 says about his destiny, and he's angry about all of that.
Another way to show that the "short time" Satan gets after being cast out of heaven is not a literal short amount of time is the fact that Christ's ascension is mentioned (Rev 12:5) just prior to the description of him being cast out of heaven. There was no place for Satan and his angels in heaven anymore once Christ ascended there. Revelation 12:10 says "for the accuser of our brethren is cast down, which accused them before our God day and night.".
Now, it's very important to consider whether or not Satan is still able to accuse us before God in heaven day and night because that will tell us a lot about the timing of him being cast out of heaven. I believe the following passage makes it abundantly clear that he cannot possibly still be accusing us before God in heaven anymore.
Romans 8:31 What, then, shall we say in response to these things? If God is for us, who can be against us? 32 He who did not spare his own Son, but gave him up for us all—how will he not also, along with him, graciously give us all things? 33 Who will bring any charge against those whom God has chosen? It is God who justifies. 34 Who then is the one who condemns? No one. Christ Jesus who died—more than that, who was raised to life—is at the right hand of God and is also interceding for us.
Who can make any accusation against God's people? No one. That would include Satan. Can this be any more clear about that? Why can no one accuse us? Because our sins are forgiven and covered by the blood of Christ. What can anyone accuse us of when that is the case? Nothing. So, Satan was cast out of heaven long ago when Christ died, rose again and ascended to the right hand of the Father in heaven.
Now, let's look at the Greek words translated as "little season" in both Revelation 6:11 and Revelation 20:3.
Revelation 6:9 And when he had opened the fifth seal, I saw under the altar the souls of them that were slain for the word of God, and for the testimony which they held: 10 And they cried with a loud voice, saying, How long, O Lord, holy and true, dost thou not judge and avenge our blood on them that dwell on the earth? 11 And white robes were given unto every one of them; and it was said unto them, that they should rest yet for a little (Greek: mikros - Strong's G3398) season (Greek: chronos - Strong's G5550), until their fellowservants also and their brethren, that should be killed as they were, should be fulfilled.
Revelation 20:3 And cast him into the bottomless pit, and shut him up, and set a seal upon him, that he should deceive the nations no more, till the thousand years should be fulfilled: and after that he must be loosed a little (Greek: mikros - Strong's G3398) season (Greek: chronos - Strong's G5550)
Notice that different Greek words are translated in Rev 6:11 and Rev 20:3 as "a little season" than are translated as "a short time" in Revelation 12:12. That's very important to note. In this case, the Greek word translated as "little" in Rev 6:11 and Rev 20:3 is "mikros" and that word, unlike "oligos", means a literal small/little number. And then the Greek word translated as "season" (chronos) in those verses refers to a period of time of any length. In this case, we know it's a "little" amount of time even though we don't know exactly how long.
So, to summarize, the "short time" of Revelation 12:12 refers to Satan's limited amount of time he has been given to try to persecute Christians since he was cast out of heaven long ago. The little season he is given after the thousand years to "deceive the nations" is a literally small amount of time rather than just a limited, but not literally small, amount of time.
My post has gotten pretty long at this point as well, but there is one last point I would like to make to show why I believe Revelation 6:11 is referring to the same "little season" Revelation 20:3.
If you read Revelation 6:9-11 you can see that the timing of it is when the fifth seal is opened. I believe the book of Revelation contains several recapitulations or parallel sections that all culminate with the return of Christ. So, I see the fifth trumpet as being parallel to the fifth seal.
Notice what happens at the fifth trumpet:
Revelation 9:1 And the fifth angel sounded, and I saw a star fall from heaven unto the earth: and to him was given the key of the bottomless pit. 2 And he opened the bottomless pit; and there arose a smoke out of the pit, as the smoke of a great furnace; and the sun and the air were darkened by reason of the smoke of the pit. 3 And there came out of the smoke locusts upon the earth: and unto them was given power, as the scorpions of the earth have power...11 And they had a king over them, which is the angel of the bottomless pit, whose name in the Hebrew tongue is Abaddon, but in the Greek tongue hath his name Apollyon.
We know that Revelation 20 says that the dragon, Satan, is cast into the bottomless pit for a "thousand years" and is loosed when the thousand years end. And here in this passage, at the fifth trumpet, which we agree occurs before the return of Christ, the bottomless pit is opened. It has previously been sealed and locked which is exactly what is described in Rev 20:3 which says the dragon, Satan, is cast there to "shut him up, and set a seal upon him".
So, to me, Revelation 9 is describing the time when the fifth seal is opened and the fifth trumpet sounds and the souls in heaven ask "How long, O Lord, holy and true, dost thou not judge and avenge our blood on them that dwell on the earth?" and Satan "is loosed out of his prison" (Rev 20:7).
Notice that the figurative "locusts" described in Revelation 9 have as their king "the angel of the bottomless pit". That means the locusts are angels as well. Fallen angels. Who do the fallen angels have as their king? Satan.
Revelation 12:9 And the great dragon was cast out, that old serpent, called the Devil, and Satan, which deceiveth the whole world: he was cast out into the earth, and his angels were cast out with him.
Matthew 25:41 Then shall he say also unto them on the left hand, Depart from me, ye cursed, into everlasting fire, prepared for the devil and his angels:
So, Abaddon/Apollyon (English: Destroyer) is just another name for Satan. He has many names including Lucifer, Beelzebub, that old serpent, the Devil and Satan. Abaddon or Apollyon is just another of his names. Each one describes a character trait of his. In this case it's his trait of being a destroyer of people's lives.
So, Revelation 9 shows us when Satan is loosed from the bottomless pit, which will be at the fifth trumpet (Christ returns at the seventh and last trumpet).