Yes and No...you NEED the original controller that came with YOUR copy of Realflight so the serial numbers match....

no the FMS controller won't work by itself
Yes, you can use your own TX with just about any sim, but you still need the original cables (at least with the good respectable ones)
with Realflight you set it up like a buddy box
with Aerofly Pro (which I use) it comes either with a TX or a cable... I use just the cable and use my own 14mZ on the sim......