Once you have buy REX token you just have to wait for the rex token price to goes up in the market with this formula
REX price = (Total Lent + Total Unlent) / Total REX
To withdraw the dividend you ...
If you see the system_contract::delegatebw, you will know that Stake is transfer to a third party account and make a record.
If you want do the things you mentioned:
have trusted stake account
Here is my basic incident response plan if an EOS account I control is hacked:
Regain control of the hacked account by changing the owner/active key pairs
Identify all transactions if any that were ...