http://magewars.com/jsite/forum/general-questions/2024-reverse-magic-and-timing-with-enchantments#2038 here I've found the answer to the question of, how long are you considered controller of reversed enchantment. It appears, that this effect lasts until the ond of the game (you can reveal enchantment and you have to pay it's upkeep cost).
But what it means to Warlock's Curseweaving ability?
CURSEWEAVING
Once per round, if a creature is destroyed that has 1 or more curse spells you control attached to it, you may return one of those spells to your spellbook, instead of placing it in your discard pile.
Let's say Felella is casting curse on Warlock, but he uses Reverse Magic. Than Felella dies. Does the attached curse goes to the Warlock's spellbook?
"Who is considered the caster of given spell?" is important for spells like Drain Life. If caster is not changed, it makes Drain Life first deal damage than heal the same Mage.
- Are you allowed to see, what enchantment you are reversing?
Not unless it is revealed. You actually have no choice as Reverse Magic has a red Reveal cost and it must be revealed when the trigger condition is met.
I mean, after revealing and paying the cost of Reverse Magic, but before resolving reversed spell. I think you can, since you have to determine, if new target is legal.