[Manly Man]

Just because you only feel negativity doesn't mean you can't be good, or that you can't do nice things. Sure, you don't get any emotional satisfaction over it, but you know that it's the right thing to do in that it is for greater benefit of others. Your anger is directed towards your enemies, your hatred and loathing is for the atrocities you've committed, and you concentrate on tempering your fury and abhorrence, your desire for vengeance, into something more like righteousness, delivering justice to the wicked.

Given, this sounds more suitable to justify having a mind flayer Paladin than most other classes. Come up with explanations of your own character's behavior, and you ought to go far.

For your question about the third-party psionics, you're welcome to put up what you wish, but I'll check the final product to see what level of cheese you've got.

And for your question about the Psychic Warrior and Warmind, Yes, they both can be advanced, but note that they have to have different powers. They pick from the same list, so be sure to get from one what you couldn't from the other. Keep this sort of thing going though (stacking a bunch of different psionic classes at each level), and I'll have to do something about it.

When it comes to Battle Blessing, you're more than welcome to apply it; after all, they are still Paladin spells. You could even go so far as to use the alternate class features mentioned in Unearthed Arcana or the other books (Cursebreaker anyone?) out there.