1. The Message IS a paraphrase (at least that's the term we OP's like to use for it) like The Living Bible was a few years ago. Any translation/version/paraphrase naturally reflects the opinion of the translators and includes any restrictions which may have been placed upon them by those authorizing or sponsoring the version. For example if I read a New World Version I have to remember that it is a Bible "translation" authorized by the Watchtower Society for use by Jehovah's Witnesses so I would expect it to promote JW doctrine like using "torture stake" for cross and "a god" for "God" in
John 1:1. The King James Version was authorized by a pervert for use in the Anglican Church so we have to take into account that it is a version translated by trinitarians for use in a trinitarian church and had to please Anglican hierarchy before it could be published. For a couple of examples the term "Bishop" is used for "overseer," "baptism" is used instead of given the translation of "dip" or "immerse" or "overwhelm" and the phrase "God Save the King" is used which was a common term used in England at that time.
I am not KJV only but it is my favorite and has been for over half a century. I read several versions but basically use the KJV for a plumb line by which to measure other versions.
2. yeppers, there is a comma there in our KJV and also in other translations. I had to look at several before I found one (the Message) which made the edifying and the praying in the Spirit seem like one action instead of two out of three. It is my understanding that there were no commas in the Greek text so punctuation is something supplied by the translators and could reflect their own interpretation.
And, yes, I agree that there is no Scripture that tells us how to "grow" our faith. The reference to the Thessalonian saints given was from a letter from Paul to a young church. It may have been the second epistle he wrote (1 Thessalonians being the first and Galatians the third in the opinion of some) written shortly after 1 Thessalonians. Dates I have seen are:
1 Thessalonians written August AD 51 from Athens (ref
Acts 17:14-15) or perhaps when he went on to Corinth in September AD 51 (ref
Acts 18:1). 2 Thessalonians is considered to have been written shortly afterward (maybe while Paul was still in Athens) in response to some eschatology questions in the assembly at Thessalonica.
Anyway, in our KJV it does say "...your faith groweth..." so it seems like it is possible for faith to develop and grow. Then preachers get to theorize on how to make that happen.