A) Any AWB is highly unlikely to pass. B) The current ban proposal is not the last ban. During the Clinton ban, ban-compliant uppers were not hard to get, and pre-ban parts were still made and available for pre-ban lowers. However, build-your-own ARs weren't all the rage, and internet sales weren't as big during much of the early Clinton ban.
So, in short - nobody knows yet. In the very unlikely event a ban passed, AR uppers would be available in SOME form, just no idea what form that might take.
As for your other questions, I'd suggest posting more info on your Colt. Even though you have been told it is collectible, times have changed, and it may not be as special or unique as it once was.
Any mil-spec bolt carrier will be chrome lined on the inside, and phosphated on the outside. Chroming the outside might make it easier to clean, but that's about it. Unless you get a good deal on one, I don't see it as being worth the extra money over a QUALITY mil-spec bolt group.
Never argue with an idiot. They will drag you down to their level and beat you with experience.
I contacted my Senators and Representative to voice my opposition to a new "assault weapon" ban. Did you?