It's the Assemblies of God, and they believe that speaking in tongues is the initial evidence of the infilling of the Holy Spirit, which it is as depicted in the Book of Acts.
No they do not and I'm not aware of any Pentecostal denomination that does so. It is a common misconception amongst those who don't believe in the gifts of the Holy Spirit and speaking in tongues that this is what Pentecostal denominations teach, but it is inaccurate to say the least.
Even though all mainline Pentecostal groups recognise that you do not need to speak in tongues to be saved, there are a number of sizable Pentecostal groups (who most Pentecostals tend to keep at arms length) who do believe that one must demonstrate an ability to speak in tongues before they can be deemed to be Saved. The denominations that hold to this position tend to be Oneness groups.
Well I wouldn't consider Pentecostal Oneness as representative of the Pentecostal faith. In my opinion I don't even count them as Christian, because they fail to believe in our Triune God. Sadly there are more than a few so-called Pentecostal churches that don't teach biblical accuracy or truth. One that comes to mind and is part of a larger group, is Todd Bentley. I am embarrassed to say he is Canadian.
Even though the various Oneness groups have been a thorn in the side of the Full Gospel movement due to their additional common position that we have to speak in tongues to be Saved; they are still a part of the Body of Christ where their Salvation has been assured by their ability to be speak in tongues which is the evidence of there having received the Holy Spirit. Over the years most Pentecostals and certainly Evangelicals have taken the right stance in that we tend to keep them at arms distance, but they are still members of the Body of Christ.
If you take another look at 1Cor 14:22-23 and particulary with Paul's use of σημεῖον semeion for our English word sign; when we consider that a sign can be used within the Scriptures either in a positive or a negative sense, when we connect semeion back to verse 21 where Paul makes reference to Isa 28:11, where the people of Jerusalem were confused and bewildered by the commands that the foreign invaders were giving in a strange tongue, we can connect these together, we can then understand that Paul is saying when everyone speaks in tongues during the congregational meeting, that an unsaved or cessationist visitor will understandably "say that we are mad"; where the use of uninterpreted tongues becomes a negative sign which will probably push them away from the Gospel.
The NIV clearly renders it as "foreign lips and strange tongues", and the following link for others that say similarly;
Mark 16:17 and you're assuming that because the God-fearing Jews heard their own languages and acts to that that is what the apostles were speaking when in fact there were more languages represented than the 12 apostles. The fact is God caused them to hear their own language, it wasn't that the apostles were speaking their languages.
It is definitely not the same, as neither the Old Testament or New Testament uses the words 'foreign tongue' or 'foreign language'. You are imposing your understanding on to the scriptures.
No he's applying what Isaiah said in 28:11 to this instance as far as the sounds are concerned not as far as languages are concerned. See Ellicott above.
Thayer's Definition of καινός (kainos)
The 'they' in Acts 2:1 refers to the 12 in Acts 1:26. Peter corroborates this in Acts 2:14-15 where it states;
Other tongues, γλῶσσα (glōssa), represented as spiritual by the tongues γλῶσσα (glōssa) of fire that appeared to rest on each one of them.
