1) They are no drop spindles for a gbody, but the S10 spindles are the same as a Gbody and come in drop versions.
2) Only tall lower balljoints will drop your car, and they drip it by whatever additional height you get. 1" taller valljoint drops your car by 1"
3) Yes you can change just the uppers and add tall upper ball joints. This will not effect your ride height at all.
4) Technically no, but you may want them to stiffen the suspension so you don't bottom out.
5) No, don't need different shocks.
6) Drop springs, upper control arms with tall balljoints. That's just my opinion though. Others have done it differently and been happy with their results.