Excuse me while I yawn. What time is it?
Clueless on your specific requirements as this is BanditAlley but, if all is same in chains and sprockets, there should be no need for a different chain length. Sounds like you're reducing the front and increasing the rear. You may need to move the wheel a little closer but no added links should be needed.
As for chains, it's all about personal choice. I like EK but know of many that prefer DID. O-ring or X-ring that is of proper strength for your 04 is all that is required.
Marc/Atlanta
'GSXR wannabe