While you may be able to get by with 4 mags as others have suggested get a few more. You'll always have some mags that seem to work better with your particular CZ than others. You'll ideally want to run say your best 4 on your belt rig, with 1 of the not so smooth mags as say your stripper mag, and as a backup, where the smoothness of the insertion and mag drop are as smooth as possible during the course and competition. I like 6, I usually have 4 on my rig, 1 stripper, and 1 backup for when you inevitably drop the mag and it gets dirty/muddy or when a plastic based mag eventually cracks.
I run a DAA belt, I'm happy with it. But then again I've never run a CR Speed which I hear are comparable. I run pretty basic mag pouches. I don't find a huge advantage for me with using those adjustable retention ones so I haven't justified buying them yet, but some people swear by them. I also see a lot people losing adjuster screws, and having weird adjustment problems with them as well so I've been wary of that. But since someone else is paying for it, couldn't hurt to get some and try them out.
It's also nice to have an electronic ear-muff that will allows you to easily hear your instructor while also muffling when shooting is taking place, as opposed to having to take off and put on your hearing protection repeatedly.
Maybe not quite "gear", but I prefer to use a ball cap so that errant ejected cases that may actually hit my head/eye protection will typically just bounce of the brim if/when it does happen. I prefer to have a number of different shades of safety glasses depending on indoor/outdoor, overcast, extremely sunny clear skies, etc. The course is usually a really long Saturday with a shorter Sunday. Bring lots of water, and dress for the weather. Fatigue and dealing with hot/cold make the course that much harder. Other than that just make sure you're comfortab'e/familiar with your gear, and maybe spend a little range time shooting at 25m, with a timer say 2 shots at 25m from the holster within 4 seconds, then 3.5, then 3. If you can handle that you should be fine. Maybe practice a little "dry-fire" drawing from the holster and dry firing at a target. I still regularly practice this before a competition. Either way you'll learn a lot in the course, and have fun. Oh and welcome to IPSC.