Garments fouling the holster: this is a common rookie issue, and you need to figure out how to eliminate it. For competition, the simple answer is to tuck your outerwear inside your belts. Always holster "slowly, deliberately, and reluctantly" while confirming that the holster is clear.
I recommend the Henning or Springer holster hangers over the Boss, unless you are female or very "large". The Boss has a cant adjustment that allows adjustment of the holster in the roll axis, which is often required for women with hips. But the Boss also hangs down, and hits the leg. It's uncomfortable and restrictive--especially if you run your holster towards the 2:00. For those of us who suffer from chronic asslessness @
GJM, there's no need to adjust the holster angle because our bodies are straight, so the simpler Henning or Springer hangers are best.
USPSA is really fun. I think you'll find people helpful and welcoming. Don't worry about being competitive for a while. You'll notice that the top shooters are super fast and accurate, but also remarkably relaxed. Trying to go fast leads to tension, and tension leads to all sorts of bad things when it comes to shooting. Shoot in your comfort zone, and you'll be surprised how soon your match placement starts moving up.