Elder-Basilisk
First Post
Combat Casting
Combat Reflexes, Expert Tactician
Divine Might
Very good choices which build effectively on the limited synergies of your classes
Divine Vigor
You'd have to wait until well into Sacred Exorcist levels to take this. And by that point, you've better ways to get the enhancement bonus to con (Endurance or bracers of health) and a bonus to speed (Expeditious retreat)
Energy Substitution,
Usually a good feat for a sorceror but you're focussing on melee rather than area effect spells. Plus you don't have any elemental spells on your list right now.
Energy Admixture
Double empower your spells instead for the same double damage but all in one energy type (thereby avoiding having your spell hit two types of elemental resistance). You don't have any elemental spells on your list right now either.
Eschew Materials
Not worth it. Spend the 5 gp for a spell component pouch instead.
Expertise, Superior Expertise, Chink in the Armor
Int is the last stat that you'll find useful as a paladin/sorceror. A 13 int is something of a waste. . . . And you've got a lot of ways to improve your AC anyway.
Chink in the armor is only useful if you're going to have trouble hitting. You should be able to construct your character so that he doesn't.
Extend Spell, Persistant Spell
Excellent choices. Persistent Shield will be your friend. If you can stand a 20% miss chance eating your breakfast Persistent Blink would be even better.
Improved Initiative
Not too useful. It's not as if you're going to have a monster dex to back it up so just get used to the fact that you'll often go late in the intiative order. (It only makes a difference on the first turn anyway).
Leadership
A good feat if the party's small but it bogs gameplay down if you've already got a large party.
Lightning Reflexes
If a paladin/sorceror can afford to blow a feat on improving saves, he's not using his feats effectively (your charisma and your vest of resistance will give you good saves; don't worry about this)
Quicken Spell
Good for magic missile as long as you have arcane preparation. Persistent spell covers a lot of the same ground for defensive spells though.
Repeat Spell
With True Strike, it appears you thought of a use for this feat. I don't see it as particularly useful for any other spells though.
Spell Focus, Greater Spell Focus/Chain Spell
Spell focus feats are only useful if you use a lot of spells with saves. Chain spell will be good for Haste but what else will you use it for? (IIRC GMW has a range of touch and is therefore ineligable for use with this feat).
Sculpt Spell/Enlarge Spell
Get sculpt spell if you're thinking of either of these. It's far far far better than enlarge spell. Of course, I don't see any damaging spells other than magic missile on your spell list so I don't see you using it.
1st - true strike, shield, magic missile, color spray
By high levels, Color Spray won't be useful anymore. Think of picking up Feather Fall instead. It will still be useful and you can use it on other people too (most items that contain it use up valuable slots and can't help other people). I'd consider picking up Expeditious Retreat as well. You can make it persistent and constantly be at double movement.
2nd - web
See Invisibility and Glitterdust as well. Every character higher than 5th level needs a way to deal with invisibility. Glitterdust will also double as Mass Blindness too. You may well want Blindness/Deafness on top of this (no somatic component and it's a good spell).
3rd - haste, blink
I'd add slow to this list--use it to counter your foes' mass Haste spells. Consider greater Magic Weapon as well.
4th - polymorph self
Fire Shield is also a good option for a melee character (assuming there's a reasonable chance that a foe might hit you). Improved Invisibility would be a good spell to know if you don't pick up the normal invisibility. Pick up Dimension Door too if you won't get another teleport style spell.
5th - wall of force
Teleport and Energy Buffer are also must have spells at this level.
6th - tensor's transformation, greater dispelling, summon monster VI
7th - limited wish
8th - mind blank
9th - time stop
I am not including the spells I will get from the exorcism domain from S.E. PrC. IDHMBWM and am unsure about the usefulness of mindblank. Will PfE and nondetection accomplish the same thing?
PfE and Nondetection don't come close to the utility of Mind Blank. The first bit is this: nondetection allows a caster level check to overcome its protection. Mind Blank doesn't. Protection from evil only protects against domination and telepathy. Mind Blank grants total immunity to all mind-effecting spells. On top of that, even at clvl 17 and extended 8 times to be a 9th level spell, protection from evil only lasts a few hours. Mind Blank lasts 24 hours. So Mind Blank is superior protection for a much longer time period. Plus it doesn't have a notable material component like non-detection.