Catherine,
I had DH put it together as "standard" (they give you two lengths of middle bar in between the stands) and I felt "squished" and uncomfortable in there. He took it apart and added the olympic size middle bar and it was much more comfortable.
The bench is easy to move around, I do it all the time. I've never tried moving the squat rack because I keep it loaded with four heavy plates on the weight poles (see my pic). I'll try unloading it and moving it around and let you know, okay.
The bench itself is very stable. I can do tricep dips off it and it doesn't move. The leg extension is very smooth but I have trouble using it for leg curls. I had ACL reconstruction though, and ANY hamstring curl is uncomfortable (so take that with a grain of salt).
HTH, let me know if you have any other questions.
Kathy