Some things i'm slightly confused about

[BRKNdevil]

One thing I'm confused about is what happens, when a caster gets say 8th level spellcasting at lvl 20 and then continues to progress into epic? Does their casting continue to progress till they hit 9th level spells? Does their caster level sorta drop when that happens since its every other level at that point? does practiced spellcaster make up for the 1/2 progression of spellcasting?

Also what happens when a say fighter decides to pick up wizard levels after epic?

[Kelb_Panthera]

For the most part becoming an epic character only means switching to the epic progression for HD related benefits; BAB, and base saving throw bonuses. Everything else continues as normal until/unless you get either all 20 levels of a base class or all 10 levels in a 10 level PrC. If your caster is only 15-16 levels into his casting class then he'll still get the same improvements to that class' spellcasting ability over the next 4-5 levels that he would have if he were a nom-epic character. Even after reaching the full 20 levels of his spellcasting progression, his caster level for those spells will still continue to rise at a rate of 1cl per casting class/PrC level (barring any obvious pattern in the PrC casting advancement).

[DrMartin]

As far as I know, the only think that get disjointed from class progression when you get to character level >20 are base attack and base saves. So a Fighter 4 / Wizard 16 that gains his 17th level as a wizard would gain access to 9th level spell, and have a caster level of 17.
This is also the case if a wizard 20 decides to level up as a cleric: he would get all the normal features a 1st level cleric gets (spells, domain, turning...) except saves and BAB.

I don't get what you mean by caster level progressing every other level - the example in the rules refers as a paladin, that normally advances caster level at 1/2 rate. The wizard in the same example advances his caster level normally.

edit: epic ninja-ed

[BRKNdevil]

says for 21st levels of progression in epic wizards, you progress every other level in caster level, so 21 levels of wizard gives you a 21 caster level, but a 23 level gives you 22 caster level

[Kelb_Panthera]

Where are you getting that?

[Evolved Shrimp]

You have to distinguish two things here, getting to epic level and getting to the end of a class progression. Both by default occur at level 20, but have little to do with each other beyond that.

Getting to epic is triggered by the character level. When it reaches 21, the character becomes epic. This has limited practical consequences: BAB and saves no longer increase by class; there is a fixed epic bonus determined by character level instead. And certain feats become available. Apart from the change in BAB and save progression, there is no effect on getting class features.

Getting to the end of a class progression is triggered by class level. When a character reaches the highest level of a given class progression – 20 for base classes, 10 for many prestige classes – getting additional levels offers only limited benefits. (Progressing beyond the highest published level of a class is possible for all base classes and for prestige classes with at least 10 levels, but not for prestige classes with fewer levels.)

Basically, any additional progress is simply inertia: When there are features that were gained every x levels, they continue to be gained at the same pace. So a fighter gains a bonus feat every other level; that still is the case for class levels beyond 20. The wizard gets +1 caster level every level and continues to do so beyond class level 20, the rogue increases her sneak attack damage, and so on.

What doesn’t continue is one-off and irregular stuff like getting trapfinding (rogue) or gaining an animal companion (ranger). There is nothing new like that beyond the end of the published class progression. Also, notably, neither spells per day nor spells known increase for any spellcasting class.

For example, a fighter 5/wizard 25 (class levels 5 and 25, character level 30) is an epic character with all the capabilities of a fifth-level fighter, the spells per day of a 20th-level wizard (because spells per day don’t increase after class level 20), and a wizard caster level of 25 (because caster level continues to increase).