What is the time length for delegated harvesting (i.e. do you need to renew it periodically like with NXT forging leases)
I assume I can turn off my PC and my stake will still be harvesting on the delegated account, is that true?
One time only transaction. It takes 6 hours to be finalized and then will last for the life of the account.
if you import your private key into another wallet and use a new nis, i think you might have to activate it again. not sure though.