Your spells are actually quite balanced. The closest thing I can find to them is Necrotic Skull Bomb from Champions of Ruin, and these are fairly balanced compared to it with one exception. Necrosis Infinitum has a better effect than NSB, which is one level higher. It is arguable that the single-target nature of it balances though.
The feats are, in a word, amazing. I can't think of a necromancer who wouldn't take them if they had the feats open. Although, you may want to edit Speedy Necroshape. There is a variant Zombie in Libris Mortis that doesn't have the partial actions only effect.