+"i guess what i'm saying is that i'm not exchanging it, in which i'm afraid of risking getting something worse."+
From all that I've personally experienced, and what I've read others experience, if your 3G S is simply "warmer" than a 3G, you've got what seems to be the 'intended calibration'. If the screen is also bright, with no polarization, has rich colors and good contrast between whites and blacks, then IMO, you've got one of the rare gems (like my wife luckily also got) and I'm happy for you, while at the same time jealous. And yes, you'd most likely end up with something worse if you tried to exchange it. Too many others, including myself, have had this problem. 😟
+"although i'm curious of the people that claims to have the very yellowish screen. if it's no trouble, can you some of you maybe post photographs here? maybe mine is really good, and i'm just being anal about it. thanks in advance."+
Scroll back through this thread to see the pics I posted and pics from at least one other person, possibly 1-2 more, showing two 3G S's side by side (a "proper" comparison IMO is a 3G S vs. 3G S, not a 3G S vs. a 3G).
As far as your battery issue, you'll by now have found the several other relevant threads. In a nutshell, I'd make sure to fully discharge your battery then do a full recharge. IMO, do this at least 2 times before concluding your battery is bad. Also, consider turning off wifi, bluetooth and location services if you don't use them, or until you need to use them.