Regarding the T-Shirts.
I bought one of the $6 dry-packaged ones the other week, washed it, and it fits really great. Perfect length, but the sleeves are just a tad longer that I would like. Not too tight in the chest or shoulders. You are correct about them being thin though.
I want to try out the premium Ts as well. If I'm a XS in the dry-packaged, should I get a S in the premium them? Or just stick with XS.