Yes - you certainly can use rulers. Handiquilter sells long arm rulers that work. The key is the ruler needs to be 1/4 inch thick - so you can't use the ruler you would use with your rotary trimmer. This is so that you don't accidentally slide the ruler under the hopping foot and create a timing problem (or worse). It takes a bit of coordination to figure out how to move the ruler with the fabric, but it really can be done with just 2 hands.
I've got superior on my machine now, and King Tut in line for the next project. The SS is very open to a variety of threads.
Have you joined the Yahoo group? There is a wealth of information through there.
Cheers, K