You can add your friend's address into your Paypal address book and make sure you select that address upon checking out.
Yes. It is possible but there is a limit though. Upon using up the limit, you are required to have your Paypal account verified so you can ccontinue to withdraw money back to your Malaysia bank account.
No. You can't.
You must check what is the minimum balance must be kept in your debit card first.

Anyway, just charge the items you want to buy to your debit card via Paypal. Paypal will deduct the money inside your Paypal account first and charge the remaining balance to your linked/chosen debit card.