There seems to be a theme. Jesus Christ and His apostles clearly stated the Great Commandment.
Is morality only in regard to man's relationship with man and not man's relationship with God? If so, then the first four of the Ten Commandments would not be moral commands, including the command against idolatry. However, if morality is also in regard to man's relationship with God, then all of God's commands are inherently moral commands, and indeed God is the basis for morality. The Bible does not differentiate between moral and non-moral commands of God, but rather disobedience to any of His commands is immoral.
They asked Jesus what the greatest command was, not which command should be obeying to the exclusion of the other commands. The greatest two commands are the greatest two commands because they are essentially what the law is about. All of God's laws can be divided into commands about how to love God and how to love your neighbor. For instance, the first four of the Ten Commandments are about how to love God and the last six are about how to love your neighbor. Jesus said that the rest of the laws hang on the greatest two because they are examples for how to obey the greatest two. The law is about how to love and the rest of the commands are commentary for how to do that.
Matthew 5 went into quite some detail on our moral relationships with God and with fellow man.
Where are the affirmations of purity laws, heave offerings, festival keeping? Not there. You have to operate from the implied and not specified. Operating from an implied 'silence' is exactly what cult leaders do with Holy Scriptures. For example Herbert Armstrong, the Mormons, you name them.
In Matthew 5, Jesus was explaining how to understand and obey the law. He specifically said that not the least part of the law would disappear until heaven and earth passed away and all is accomplished, which is either saying that the least part will never pass away or is referring to end times. Jesus also warned those who would relax the least of the laws and teach others to do the same. So there is no need to rely on implication when it is clearly stated to still be in effect (heaven and earth as still here and not all has been accomplished), but there is plenty of solid implication.
The law is what gives us knowledge of sin (Romans 3:20), without the law we wouldn't even know what sin was (Romans 7:7), sin is defined as lawlessness (1 John 3:4), and we are told not to sin (Romans 6:15), so it is a straightforward inference inference that we are told not to break the law, which includes keeping the festivals. The law is God's instructions for how to have a holy, righteous, and good conduct (Romans 7:12) and as part of the New Covenant we are also told to have a holy, righteous, and good conduct (1 Peter 1:14-16, 1 John 3:10, Ephesians 2:10). Furthermore, the New Covenant involves God writing His law on our hearts so that we will obey it (Jeremiah 31:33). Jesus gave us a perfect example of how to obey the law and we are told to follow his example (1 Peter 2:21-22), to follow his commands and walk as he walked (1 John 2:4-6), and to become imitations of him (1 Corinthians 11:1). We can not be his disciples if we refuse to follow his example.
613 laws I believe in Torah. How many can a post Temple Jew or Christian observe? What of the civil laws? We are not a theocracy, yet those Israelite theocratic laws sure do instruct and tutor us on the Mind of God and His Holy standard.
Festivals? All the Spring festivals are fulfilled. What Christian does not each day celebrate in their deliverance from the second death and rejoice in the first fruits of the Resurrection? Who does not step out each day and rejoice in the Holy Spirit given gifts and do the works God sets forth for us as the first Spirit filled believers did on Pentecost? Living each day as we are being poured out as a drink offering?
Yes the Fall festivals are yet to be fulfilled. What Christian does not rejoice in knowing Messiah will return in Glory and Power with Justice; to bring those of His sheep to mansions in His Kingdom? We watch each day, in hope more will become disciples of Messiah and join us in His Kingdom. Thus our mission of the Great Commission. Yes the King is coming again!
If you wish to celebrate old covenant observances, you are at liberty to do so. I stated above that such observances are daily and in the heart, as Christ told us "the Kingdom of is within you."
Again, the Bible makes no distinction between civil and non-civil laws, but rather sin is disobedience to any of God's laws. To fulfill the festivals means to bring full meaning to them. For instance, as our Passover Lamb, Jesus brought full meaning to Passover, so he made it all the more important to keep now that we fully understand it. The Festivals are rich with teachings about the Messiah and they are a joy to keep, so is only to your extreme detriment to not keep them in accordance with Jesus and Paul's example. Moses could not have used daily observances to lamely excuse his sin in disobedience to God's commands and neither can we.