You cannot move IOTA's that are not confirmed to one of your addresses - so you have to wait for confirmation before sending it on.
It's recommended to create a new address for each incoming transfer because -
If you get two to same address, the first may conrift fast, and second can be pending for a while . If you then spend the first arrivals before second is confirmed, you will receive to an address already 'used' when second trnasfer is confirmed. This will lead to a key-reuse when you try to spend the second arrivals.