So do the SPV miners still get the transaction money even though they haven't verified? What happens when it becomes too difficult to find new blocks, will it be impossible to transfer Bitcoins?
As long as the previous block follows the network rules and it doesn't get orphaned. SPV mining deducts the time used for verifying. They assume that the longest chain is valid.*
Difficulty automatically adjusts to make the blocks to go to 10 minute intervals. If it's faster, it will increase and vice versa. However, if a large miner decides to shut down their farm, it can get affected. Only if 50% of the network shuts down, blocks would be twice as long for 2016 blocks. The transaction speed of Bitcoin is instant, confirmation is not.
*Mining pool runs a full node but due to how SPV works, they will continue to mine on invalid chain.