Still spell removes the somatic component from spells. In practical terms this results in the arcane spell failure from wearing armor not applying to spells cast as still spells. If you're not planning to have your wizard wear armor beyond robes then there's no reason to take this feat. Similarly, silent spell removes the verbal component requirement from spells. In practical terms it means that silent spells can still be cast even if your wizard gets hit with Silence. I don't recall many enemies using Silence in the game, so there's not much reason to take this feat either.

Heightened spell results in a lower-level spell being treated as a higher-level spell. On the negative side it occupies a higher level spell slot, and on the positive side it has a higher DC and also can get around defensive spells that block lower level spells (such as Lesser Glove of Invulnerability). I personally wouldn't consider Heightened spell a particularly useful feat.

Finally, clerics can craft holy weapons, but they need to have taken the Good domain in order to do so (for the Holy Smite spell that's necessary for the crafting).