I just went and checked my setup. The base of my machine is flush with the front of the carriage and overhangs the back of the carriage by 1". There is 1" of space to the right and left of the machine (that is, more carriage than machine).
I'm not sure what you mean by "feet"; I don't think there are any feet underneath the base of my machine. However, I'm not picking up that 70-lb monster to check!
Dh lifted and centered the machine for me.
One thing you want to do is get a level and check that the frame is level from front-to-back and end-to-end. Ideally the machine and carriage should stay put no matter where you stop it. If the frame is not level, the machine will slide from the position in which you place it.