Welcome to the SB world! I think you'll enjoy it.
First off, I'd take a look at Task Force Echo 4 (a bit of self-promoting, perhaps) and poke around. There are some really good game resources, including some documents designed for inexperienced players to read.
Grunt School is a great article and really gives a new guy a perspective on the game. Here are the article archives.
http://tfe4.wordpress.com/supply-section...-archives/
I'll address some of your other questions when I have a bit more non-work time. I'm sure others will chime in as well.
I'd also spend some time reading the manual, if you haven't. It really is chock-full of good information, and it may answer some of your questions. Make sure to patch your games to the most recent version on the HPS Website as well. There have been quite a few changes since TOD first released....