Possession and essence. Options

[emo samurai]

I have about 50 questions about the possession metamagic. First, if a mage possesses a dude with cyber, does he cast spells as if he had the reduced essence or his normal essence? And can a mage possess a cyberzombie without a ritual that binds him permanently to the body? And if the body dies, does the dude possessing it die, too?

Also, here's an idea for a campaign nuisance. I'm thinking of having a prime runner. He's a really uber-vicious troll who's famous in the Barrens for being an incredibly horrific enforcer-for-hire. He was very skilled and tough, but he was content to be paid about a tenth of what he'd normally get killing gangsters by the dozens. It was his paid hobby. Then, a few months back, he came down with a curious case of wanderlust that was completely uncharacteristic of him. He came back speaking Aztlaner and knowledgeable of many things he never showed an interest in before, including high Aztlaner etiquette. He seemed detached, as if he were another person who had learned to act like the troll dude from rumors and stories of him. Even if he had the body, he just wasn't... him. He'll turn out to be an Aztechnology blood mage who uses the body as a way to have lots of risk-free fun. Every time the dude gets killed by the runners, the troll will come back with more cyber until he's a cyberzombie. When the body's finally destroyed completely, the mage will come after them himself in a fit of wounded pride and stupidity. The players will capture him and get the 1 million nuyen bounty.

Is the above megaparagraph plausible?