Oh, yes, for reining, a bit heavier split rein than you normally would use helps guide the horse , is less noodley than thinner ones and gives more direct signals when slack/drapey.
Most use split reins, but some use romal ones also.
Re jeans. I came from the dressage world and always wore FITS full seat breeches. I have issues with mu Lee and Walmart jeans. I bought a pair of these https://www.ridingwarehouse.com/Ariat_Womens_REAL_Boot_Cut_Cooling_Rosa_Lita_Jeans/descpage-ABRO.html and I LOVE them! Ariat adds an extra inch to the length so their longs are 35" and extra longs are 37"! The waist of these jeans sit at your belly button and are much more flattering than the lower cut ones. They are cooler than most jeans and have some stretch in them. They do get a tad loose after a couple of rides, but tighten up in the dryer. And, they do not shrink to a smaller size than when new. I just ordered another pair!
Coming from English-land, even Ariat and Wrangler jeans have too noticeable seams for me, plus generally just feel too thick and stiff. I lived my Goode Rider denim breeches, and was happy to see they have a bootcut version with no inner seam! No knee patches either so they look like regular western jeans. I’m 5’2" with smaller waist compared to hips and they fit well (stack in the saddle), but are probably too short for longer legged ladies.
https://www.smartpakequine.com/pt/goode-rider-equestrian-bootcut-jean-24306
I love my Ariat Rosa Lita jeans. The come up higher and you don’t get the plumber’s Crack when you ride. They do have some stretch in them and they will stretch out a little bit but tighten right up when you wash and dry them. They never get smaller. I love mine and have 2 pair.
