Bought iPhone 3G one week ago

Bought my 3G on may 29th. The AT&T store that I bought my iphone from stinks and wont pick up after 6 calls over an hours time.
A good friend of mine who has had the 3G since the 1st day it came out told me (a few weeks ago), that the new iPhone is coming out, however I can still download the new OS 3.0. I took that for granted and thought, meh, I just want it NOW and surely the new update will be fine. LOL @ ME, the new S model is sick. Like a turbocharged version basically. 200hp motor, or 300 hp motor, for same price...?!
Ive been browsing around on here and want to confirm that this is true:
If I pre-order the iPhone 3G S (should do within the next few days, its hot), then take my originally bought 3G to my AT&T store, they will charge me a $20 restocking fee, and just exchange the phones.
If I dont plan on getting the 3G S, and choose to keep my 3G, then I can just go to my store and get $100 store credit (I doubt cash?)
Final question (of greater unknowing to me): I just registered my extended protection plan (2 years of warranty) a few days ago. That was $70. Not cheap. Would they transfer that over to my new iphone, or just completely ignore the fact that I spent $70 for an extended warranty? I could picture a big company like Apple trying to milk every dollar out of users.
P.S. I FREAKING love the iPhone, I mostly love playing games (Sims 3, and NFSUndercover) and it runs great. But the new features of the 3G S (not to mention 16GB rather than 8GB) just makes it a no brainer for anyone who uses their iphone at all.
P.S.S, I feel really bad for those out of luck who has gone past their 30 day grace period (or will very soon)... things happen and technology is ALWAYS being updated.
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