Just make them not outright replacements.
I mean, would Invisibility utterly ruined for all time if instead of giving total invisibility, it gave a 10+1/2 caster level (or something) bonus on hide checks?
For me, a giant yes for prepared casting. My favourite archetype by far. I love the mechanic, too. or the idea behind it. The wizard is the scholar of the game. The most intelligent guy around. He studies magic scientifically and prepares what he needs for the situation. I love it. It provides so many fluff opportunities too. Because I mean, really. Have you ever seen another mechanic that emphasises "this guy is smart" that much?
Spellpoint systems make me go uuuurgh. They are so... boring.
Skills: yes on open lock/disable device, but Seeing and Hearing are different things and should be different skills. But I don't think I've ever seen anyone use Appraise. That should just be a knowledge or craft skill or something.