1. Why I'm able to reuse the session token even if i've destroyed them ?
I've tested this, and indeed, after destroying a session I can restore the session, after which it gives me the same deposit address. It resets the timer to the full 48 hours though.
I haven't tested this with a funded session, I don't dare to destroy that session just to test it.
2. How i can export private keys in an existing wallet on electrum? Does it work with the local sweep function?
Did you mean "import" instead of "export"? You can sweep the private key into an existing Electrum wallet. After this, the funds are transfered to a new address within your wallet.[/quote]