What skills should I already know prior to taking this aid climbing class?

Ideally having a strong background in free climbing is helpful. Even the easiest aid climbs usually have some free climbing involved but if you can lead 5.9 on gear then you are capable of climbing a variety of classic aid routes. If you're not already comfortable with anchor building and transitions or leading on gear then something like our Trad Leading Course or a Multipitch Skills Clinic might be a better place to start.

What kind of haul systems will I learn?

If you are just getting started we generally focus on the two simplest systems, a 1:1 and 3:1 and some variations on those. If you've got some experience we can delve into more complicated mechanical advantage systems but those two generally cover 90% of what beginning aid climbers need to know.

Will I learn to set up a portaledge?

This isn't typically something we teach. We generally recommend beginners start with routes that can be accomplished in a day or have big enough ledges to sleep on til they have the other complicated logistics down. If you have a ledge and want help learning to set it up we're happy to work through that but there are some variations so we may have to gain familiarity with any specific system first.

Will this be enough to climb a wall in Yosemite or Zion?

It really depends on your current skills. If you are a competent trad leader and comfortable with a variety of rope systems then this could just be enough to give you the tools for a shorter objective where you can fix and fire like Leaning Tower in Yosemite or Spaceshot in Zion. It would be a real struggle to do an overnight route with multiple large haul bags, difficult aid moves, or setting up ledges but potentially something like Washington Column or Touchstone Wall. If you're very new to leading then we would probably suggest doing something like aiding shorter, less popular, free routes to gain efficiency and greater familiarity with the systems after the initial course.