Okay, here goes...
1. I don't quote max tire dimensions because every tire company measures differently. I've got a 2.3" Nokian NBX on the back of mine, and there's plenty of clearance. So just figure pretty darn big.
2. Getting a different rocker for the bike from us will not increase the travel. The stays are different lengths, as are the placement and stroke of the shock. So everything would have to be changed. The aftermarket doohickeys (yes, i believe that is a technical term) that some company sells only make the tire rub on the seat tube and void your warranty. Plus, they change the way the shock moves, and not in a positive manner. Our Product Manager is extremely anal about shock setup, so our bikes' rear suspensions come about as dialed as can be for what they are. Change one of those variables, as in the rocker arm length, and everything changes.
3. See the verbose answer above.
4. Again, back to #2. (Can you tell that i REALLY don't recommend these rockers? Can you also tell that i've had a beer or two?
5. It's a phenomenal climber. We have a lot of hills around here, and the Dawg is the most common bike on the trails here. Also, let me mention that the different rockers would also change how active the shock is, and could make the bike bob when climbing, something it does not do now.
It's up to you on whether you want to buy now or wait. I have an '04 and love it. I'll actually be keeping it over an '05, but that's me. The Dawg Primo has a Talas fork that goes to 5" up front, and with that and 4" in back, i've never ridden a better trailbike. That's not jsut marketing speak. I wouldn't be here if i didn't love the bikes we make, and the Dawg (or DL, Primo, that platform) is my favorite mountain bike we make, hands down. Again, for me.
The '05s won't be out until October or so, so factor in what riding time you'd get in before then.
Thanks, and let me know if you have any more questions, or just visit your local Kona dealer, Acme Bikes.
Joe.