I'd say Combat Casting is actually a bad idea. By level 35, you can have 38 ranks in Concentration, which means you automatically succeed on the concentration check to cast any spell defensively.
Yeah I might be begging but unlike the guys on the street, I'm not like desperate to keep this character. But I do appreciate the fact you and others have taken the time to look at this character to give me some ideas.
Would you prefer a blaster, buffer, summoner, battlefield controller or more of a Generalist?
Here's a small list of 'essential' feats for any epic level arcane caster:
Epic Spellcasting (this is a no-brainer)
Improved Spell Capacity (until you qualify for Imp. Metamagic)
Improved Metamagic (take this at least once, preferably two-to-three times)
Persistant Spell (24 hour buffs are necessary in epic play)
Quicken Spell (multiple spells per round will help take care of the opposition more quickly)
Arcane Mastery (never fail a Spell Resistance tjeck)
Craft Contingent Spell (an answer for anything your prepared spells can't handle and much, much more)
I figure my Wizard levels would be based on spells for various "need" type things. My sorcerer known spells would be more inclined to "Must have spells for combat."
Because your CL for Wizard will be 20 and your Sorcerer CL will be 22. Practiced Spellcaster could bring those up to 24 and 26. This helps against dispels, SR, and for certain spells that scale above CL 20, like Horrid Wilting.
You need it to A) overcome your caster level hit initially, and B) to manipulate progression of ultimate magus. The UM doesn't give full casting in each class; at several points whichever of your caster levels is lower gets a level, while the higher level class gets nothing (it works out to +7/+10 IIRC). So if you use practiced spellcaster, your caster levels will be even, thus giving you the choice to advance your more powerful casting side.
You might be better off going the other way - using the sorcerer side to be able to bring out toolbox spells spontaneously, and leaving wizard with the combat stuff. One of the UM class abilities lets you burn slots from the sorcerer side to metamagic spells on the wizard side, so you could bring out heavily meta'd attack spells if your wizard side contains them.
Arcane Mastery is good, since the UM gets +4 caster level (not for spellcasting though). Since your caster level is generally going to be above your actual level, taking 10 is a good bet. That being said, however, Epic monsters often have crazy SR so it's probably a good idea to combo it with some spell pen feats and/or no SR spells (conjuration attacks)