As for basic house rules, start with these: Forget "Epic progressions" for BAB and saves. Toss 'em flat out. Continue progressions for class levels and HD as per sub-epic. Heck, monsters do this already... PCs should be no different.
Expect, with regards to attack bonuses and AC:
Full BAB progressions (Fighter, Barbarian, etc) will always hit unless they power attack too much. In this case, AC actually acts as DR for the most part, by preventing too much power attack.
2/3 BAB progressions (Rogue, cleric, etc) will generally be able to hit, but not power attack any. You may find that they actually have to roll the d20 sometimes.
1/2 BAB prgressions (wizard, etc) will not be able to hit anything but touch ACs.
Many saving throws will be more or less automatic for one side or the other. Consider this in your tactics.
On the other hand, you may want to consider removing immunities from the game, replacing them all with resistances. This makes for a more interesting battlefield, because as it is, between two characters, there will be pseudo immunities between them anyway... might as well get rid of the absolute immunities, and make it possible for a dedicated character to be effective anyway in specific situations. For example, replace Energy Immunity with Energy Resistance 50, make it 100 if they also have the energy subtype, and make it 150 if they're primarily composed of the energy (like an elemental). That's
practically immunity in most cases, but with epic levels... you might have dedicated players able to get by them. This is cool. And a far better solution than just making an endless series of trumps: "This feat bypasses X immunity. This feat makes them immune anyway. This other feat makes them vulnerable anyway." back and forth, back and forth, without effecting their power against non-immune things at all, which is stupid.
You'll be interested in Upper Krust's "Immortal's Handbook", I think. The main rules should be comming out this month actually, but U_K is notorious for missing his deadlines. The Epic Bestiary, on the other hand, is already out. It may be a bestiary, but it's got a bunch of general epic rules too. It has two feats that practically replace epic spellcasting. But most importantly, it gives meaning to what a given level should look like. (Link:
Eternity Publishing)