Morris
You had some good ideas, but many of them have been said before on this thread. (and by before, I mean less than 5 pages ago)
ragdoll should be included, and more manual powered vehicles is a good idea.
But your post (or combination of 15 different posts) has a lot of "more is better" ideas, which could be the downfall of the series. R* has plenty of technical things to impove upon in GTA 4 without having to cram more and more material, areas, side missions etc. into one game. The game will undoubtably be huge, so I don't think we need say "it should be 3 times larger than SA" or whatever.
I would leave story details up to Rockstar. Some of them were ok but things of that nature are better left to the pros. The mission ideas were good though.
Try to tone the length of your posts down a bit, or break them up into digestible peices. No one wants to read/respond to all that in one sitting.
People keep talking about gas tanks..... just sounds like a hassle to me.