No, they don’t exclude each other. However, now I think that any new storage/memory that we introduce, should be linear. So if I were to write the transient storage EIP now, I would call it cross-frame memory, and make it behave like a linear memory and not like a non-linear storage. In the hindsight, the contract storage in Ethereum should have been linear too. And I seem to remember that Nick agrees with that too.
Not quite; in my opinion it should be page-table based; that fits much better with how real world memory and disk are organised, and has much lower overhead than maps.