1) I'd suggest you go through different characters' movesets and familiarize yourself with them. Learn what gatlings into what, what's punishable, any properties a move may have, etc.
2) Honestly... this is rough. Try showing off the game at local gatherings/tournaments to get ppl interested, or reach out on match finder (make a thread if there isn't one). Failing all that, you'll probably have to stick with netplay :/ (But even netplay is useful if you can find/stick to the good players)