How many rounds would it take for a 30th level character to kill a 30th level monster?
Doesn't really bother me, my games never get anywhere near that high anyway.
rounds, a 1st level character to kill a 1st level monster?
1 HIT on average. That may or not take a couple of rounds.
rounds, a 1st level monster to kill a 1st level character?
I think I agree with your 3 rounds, but again, that includes misses.
How many rounds of combat do players play before they start to get tired of it?
My answer is 3 rounds.
My answer is that it varies a huge amount on how long those rounds take in real life. I can be bored by the second round of our 4E game (because the players take so long), whereas I've had combats in my pathfinder game take 10 rounds without any loss of excitement. The difference? 1 round vs 10 rounds... and both situations took roughly the same amount of real world minutes to resolve. [please do not take this as edition bashing, I recognize that the players are a major contributing factor]
What should be the highest maximum hit points of a character?
Of a monster?
I'm torn on this one. I like the plateauing of HP in 1st and 2nd Ed, but I also like the constant progression of 3rd Ed. Simple and 'fair' as it was, 4E's flat numbers per level HP didn't sit right with me, though it was only a minor irritation.
I think I'm happier with the 3E progression; but it comes down to the caveats that I'd like added to those progressions
3E Caveat: lowest HP dice is d6, not d4.
1E-2E Caveat: Other progression points slow down at the same time that HP slow down - you're reaching the upper limits of mortal ability, and so it takes more effort/experience to improve.
The main thing in favour of stopping Hit Dice at level ~10 is that mages won't fall quite so far behind. Hence the d6 idea for 3E.
Regardless of the system chosen, I'm always happy with monsters having a wider range of HP than characters. Anywhere from 1 HP to 50 HD + 50x conmod (or the estimated equivalent thereof).
Basically, the monsters' HP should make sense. A titan/dragon/what-have-you should have a lot of HP compared to a human. And so on.
What should be the highest maximum ability scores, modifiers and level-up bonuses?
3-18 for humans. 2-19 (or perhaps 2-20?) for other races, as natural limits. Magic can take you beyond that. No stat boosts due to leveling up. Include potential adventure driven ways of increasing your stats, within the natural boundaries, whilst preventing everyone from boosting themselves up to 6 18s.
[/b]What should be the range of feat bonuses to ability scores?
+1 weapon proficiency, +1 improved, +1 weapon focus for a total of +3[/b]I think I'd like to see a complete removal of all the flat +1 feats from DND. That is, anything which gives you a +1 to hit virtually all of the time, is too powerful, and should therefore not be in the same category of character features as things like 'gain this miniscule bonus on the rare occasion that you manage to kill something with a critical hit, while within 3 squares of an ally'.
However, having just looked for examples of the kind of feats I was thinking of, I just discovered that the 3.5 PHB isn't as bad as I remembered.
Put me down as undecided on this question. I'm not even sure that I want feats at all to be honest.
What should be the maximum magical bonus from magical items?
+5
What should be the maximum damage of a power?
I haven't the faintest idea...