And yes, Paladins are restricted from knowingly associating with Evil characters.
Also, if you really want to be a Negromancer, be a Cleric, not a Wizard. Wizards suck at Negromancery. (it's useful to them as a means to get bodies to perform menial tasks and whatnot if they're planning on setting up shop somewhere, and with the right multiclassing and prestige classing you can get a decent necrowizard going, but the Cleric is far superior in almost all respects.)
I can point you to some wonderful guides on how to be a Negromancer and not suck big hairy gorilla balls, as 3.5 seems to be very carefully crafted so as to provide the illusion of being able to be a competant Negromancer and contribute to the party without actually doing so. The designers were (and still are) very big on playing the good guys, and they never really liked giving people bad guy options (as shown by the fact that they generally suck.)
But Negromancery is hard, very hard, i highly reccomend that you do not persue that path until you've gotten a decent mastery of the system. If you're determined though, then know that Negrowizards are basically 'death dealers' in that they throw around lots of nasty death effects and debuffs, but don't expect to command an Undead Army. If you want an Undead Army, you're gonna hafta be a Cleric, at least to start with.