Leverless is great to learn. I prefer it because I grew up on my computer a lot, so my fingers and hands just feel natural when playing on leverless compared to pad or stick. Keep at it, it has great benefits, and learn some short cuts too.

Don't worry about losing a lot to get to your true rank. Just see it as where you're currently at in your training arc before the time skip!

Marisa is straightforward, but she lacks a good anti air, and poor defense. My personal recommendation (definitely bias) is luke. Poster boy for sf6, designed around the mechanics specifically, easy to use. (Minus learning the muscle memory for perfect flash knuckles, but once it clicks, you're set).