I think that FSA and Shimano big rings aren't compatible anymore, though I think they used to be. The inner ring may still be compatible, provided you get the right BCD size (110 or 130).

The threaded bottom bracket insert won't slip out. If anything, it will become a permanent install, because even with a tool they make to remove it, it is very difficult to do so.

You really don't need any specific crank with your Shimano group, though Shimano milled rings would be best which includes FSA, Cannondale, Specialized, Fulcrum, Truvativ, etc. SRAM cranks should also work, but maybe don't use the newer narrow (7900, 6700 series) chains. I think all of those except maybe Fulcrum (?) has a BB30 option. My LBS is a big fan of Cannondale BB30 cranks with Shimano groups (disclosure: they are a big Cannondale dealer) because they think the rings are stiff but you don't pay the same $ as FSA. This LBS also really dislikes FSA cranksets in general.

Cranksets really aren't that finicky and are surprisingly cross-compatible among brands. A friend of mine uses a compact Campy crankset with his SRAM group.