yep was going to suggest getting a cheap fdm as well.
It's not that they are bad - fdm is an amazing technology and the sheer variety of filaments makes it an extremely useful thing to have.
But for small detailed models, resin is the way to go :-)

formlabs have actually printed clear lenses with their form2. That's impressve. It's also about 6x more expensive than the wanhao :-)

You would have problems using two different layer heights on the same layers.
What you can do is have different layer heights for different vertical heights of the print. You can also have different layer heights for different models printed at the same time. But tryig to mix different layer heights on the same levels is just asking for trouble.
Even a delta with a long thin nozzle would struggle.

They're still pretty new but the d7 looks pretty good and wanhao do have a good track record with their printers.
Definitely interested to see how you get on with it :-)