My $0.02 on a few things here....
Equipment... Don't overthink it.
1x is simpler, yes. I run a 42 / 11-32 setup. A 42/32 nearly the same as 36/28 (standard CX setup is 46/36 and 11-28). But this is kinda personal, so do what suits you best.
Fitness.... like
@Delish said, whatever you have now is gonna be about it, so work on skills. Yes, you can do intervals during the week to fine tune a little, but whatever base you have now is what you're gonna have to work with.... This will be easy for me this year, cause I have no base, and no fitness, so therefore nothing to work with. No work=easy. (until race day, then no work=FML)
Skills... There are a bunch of sessions around. I totally flaked this year on the small group I've ran for the past few years. Here's a few things to work on....
Find an open field, and as mentioned, use some cones, tennis balls. lawn flags, whatever, and do the following.
Practice starts. This isn't just the clipping in part, but also which gear to choose, where to start with the one foot already on the pedal (hint - about 10 o'clock), how to line up the rotation of the other pedal so you hit it flat as it comes around, if you stand over the top tube or sit on the saddle, and finally that initial sprint and first few gear shifts.
Figure Eights. Using two cones, about 10 yards apart, ride a figure eight, slowly at first, and gradually going faster. NO BRAKES. Lean the bike a little more every few times around, until you almost eat shit. Now change directions.
Use the cones or whatever to set up a slalom of about 10-15 cones, every 3-4 yards. Start slow, and see how fast you can go.
Barriers. Use a log, or a backpack, or whatever. Practice the approach, dismount, how you'll lift the bike, and remount. Do you stutter step? Do you leap back on, or kind of throw a leg over and slide back on? How quickly can you get clipped in and pedaling again? Did you shift to the right gear BEFORE the barrier?
Race day.. pre-ride pre-ride pre-ride. This is not a warm up. This is where you decide which line to take. Where to ride or run. This will all change as the race goes on, especially when it's already wet or raining.