I was able to solve both problems with the use of Assembly Features menu.

I used one part body to create the actual part, and another part body to create the hole around it (I’m surprised you can have a negative feature by it self in the part...)...when assembled, I used add remove to remove the hole around it from another part....

I also discovered "reuse patter" & symmetry in assembly mode and I love it (I’m a newbie - easily impressed.)