1. Is there a way to place covers faster with a sort of machine?
2. What blocks go well with fantasy blocks, marble cobblestone and light blue stained clay?
1. There is no way to place microblocks by other than hand that I know of, due to the fact that microblocks require extra information on where inside the block they are supposed to be placed. And this is only imparted through the special "ghost" layout placing that the player does.
2. Mentioned this a fair bit of times here on the forum, but a good idea is to build a large room and fill it with samples of the different kinds of building materials available. That way you can go shopping for exactly what you need, and easily compare shades of the same colour etc.
Example of my room for that: