A puck is very helpful with a pc quilter. It allows you to stop quilting from the front of your sewing machine. The standard pcquilter has the stop button on the rear of the pcquilter. It is very hard to reach from the front of the machine when a quilting emergency happens. It also lets you raise the needle up/dowh and increase/decrease the speed your sewing machine is sewing at from the front of the sewing machine.
At this point, I would not quilt without the puck. You can get a puck from Mikesmachineshop.com. They are custom made for your sewing machine.
Most quilting designer web sites have patterns that are compatible with the .txt files patterns pcquilter uses. You can also make your own patterns and convert it to a .txt file as part of the pcquilter software.
Yes, pcquilter does maintain/update software as part of a package of customer support they sell. I never updated mine - have had it 3 years and haven't had a problem that wasn't caused by operator error.