1. When you use up energy of enchantments and refill it with soul gems, where does it (the soul energy) go after the enchantment is used? Is it like electrical resistance?

2. I read that black soul gems can sometimes cause its contents to "leak" into a person holding it. So basically you get memory transplant from them? What about white souls? Could you upload scrib thoughts that way?

Maybe... There is such thing as "memory stone" exists, special for memory recording. I think that their nature is the same as soul gems. So it is possible that black souls gems has similar side effect.
Don't sure about scrib thoughts, though.

1: Probably to the Dreamsleeve.

2: Never heard of but I guess it's possible.
Would be interesting how the person acts if he would get a Scrib/Guar soul in a black soul gem.

EDIT: Nevermind, found out. http://www.imperial-library.info/obbooks/souls_black_white.shtml
1) I guess it stays until used up? All I remember is, in DF should an enchanted weapon break, the soul of the being that was used to enchant the weapon is freed and attacks you. So, if you enchanted a rusty iron knife with the soul of a golden saint, and it broke, the golden saint would be freed and probably would start kicking your ass for what you did. I'm also going to assume that applies to all people and creatures when it comes to enchanting a weapon. As for recharging, I guess it works like a battery...?

2) And no, it's the caster's soul that leaks into the black soul gem, not the soul in the BSJ that leaks into the caster.

Well that's lame, how are you going to plant scrib memories in someone's mind?

Well, soul stones seem to be more like soul vacuums, not blowers.

http://www.imperial-library.info/dfbooks/b022_memorystone.shtml?