12-52 is really heavy for E standard tuning, I think they used that in the stone age, or Jurassic or whatever. That's the sort of strings I'd use for C tuning. Of course it's partly personal preference, but after trying with different strings strengths, I'd never go beyond 10-46 (which I use for D tuning on the most common Fendery 25.5" scale, and as standard on 24.75" Gibson/Epiphone).
As for pickups, it really depends on the music you want to play. Hendrix? Sabbath? Slayer?