Not unless they are sister resorts like the 3 All Stars or Port Orleans Riverside and French Quarter. DVC members are permitted to pool hop, but with a lot of restrictions.
There is a pool hopping sticky at the top of he boards.
No. The only exceptions are when your resort has a sister resort. Such as Port Orleans Riverside and Port Orleans French Quarter. If you are staying at one, you can use the other resorts pool.
And the same goes for all 3 of the All Stars Resorts.