Use your own gun. You want to be familiar with the weapon going in, and the course will help you build on that familiarity - all of which gives you a better end result.
Don't be afraid to ask questions in the class, either. In my experience, instructors are ALWAYS gracious and happy to provide answers, no matter how "dumb" the pupil thinks the question might be.
Here in Maryland, you have to take a PAIR of classes. One, you have to take in order to even BUY a handgun - that's the HQL class, or Handgun Qualification License. Then, there's the wear-and-carry class (Maryland does not distinguish between concealed and open carry, so it is not a CCW class but a wear-and-carry class). HQL is a pre-requisite for w&c.
I took both classes together, so I'm not 100% sure on which class required the live-fire work...but I know that in order to do the whole process, I was required to shoot a live fire target consisting of 50 rounds at varying distances. The state requires one target; the range where I took the courses required four. Repetitive, but...not exactly a nuisance to "have" to shoot 200 rounds at the range! Scoring - and my understanding is, this is a "standard" target setup - is anything in the 8-ring or better is 5 points. 7-ring is 4 points. 6-ring is 3. Outside that, 1 point. Perfect score is 250 - 50 rounds, inside the 8 ring, 5 points each.
I had put five rounds through my XDs - total - before lining up for my live fire qualifications. I shot a 250, a 248, a 248, and a 250.
But, the live fire is only PART of the equation. The classroom side is HUGE - legal ramifications, definitions of "castle doctrine", "stand your ground", and other pertinent phrases. State law regarding use of force. State law regarding transport, carry, display/concealment. State law regarding establishments that serve liquor. State law regarding "no firearms" signs on businesses - do they have force of law and you can get arrested? Or are they business preferences and all they can do is ask you to leave the premises? What do you do when you are in a traffic stop, and carrying your weapon? It is ALL covered in the class...and you DEFINITELY want to be alert for all of it. The classroom is likely more important than the live-fire portion, when it comes down to YOUR life after an incident.