The difficulty won't drop, because miners with less than 1M SC can't mine trusted blocks. So it hasn't any effect on the actual blocks/time. You can decide to not mine SC, and the difficulty will drop a little bit.
The difficulty will drop. The difficulty for trusted blocks and normal blocks isn't related.
Yep, they are not related. You can't affect the difficulty by trying to mine/not mine trusted blocks, because you can't solve one withouth 1M SC, it doesn't matter if you stop the miner on even blocks or not. So you can only affect the SC difficulty by mining/not mining odd blocks. But you can stop the miner on even blocks and switch to some other chain until the trusted block is solved.