I'll just play devil's advocate because this is something that always interested me. When I started playing, I quickly became a j"ack of all trades, master of none" kind of golfer b/c my home course required so many different lines to get out of trouble and save par and such. So I got a competent BH, FH, and OH but really it wasn't until I buckled down and really worked on the BH that I felt like I reached a new level. Of course, I focused on the BH so much that my FH and OH got rusty and now I've got to pick them back up.
So I guess it kind of depends on the person is what I'm trying to say, because for me personally, I feel like it would have shortened my learning curve dramatically if I had really figured out the BH first instead of using FH and OH as sorts of form shortcuts. Interesting to think about.
Just about anything out of the box understable really. DX Leopard is what most people usually start out with. A beat Roc can do them easily, Comet if you don't have one beat in enough.
Hyzer flip is pretty much any understable disc thrown with hyzer that if thrown with enough power/fast enough will flip out of hyzer to flat or even all the way over, depending on stability and amount of power used. A hyzer flip that doesn't end straight or fade back at the end is basically a turnover, i.e. turned over into an anhyzer angle and stayed turned over. A hyzer flip is a fantastically useful line and really teaches you about line shaping because you can control just about every aspect of the disc's flight (amount or duration of turn, amount or duration of fade). Practice throwing hyzers that flip flat and fade back, flip flat and stay straight, turn over a little and track right, turn over and "fade" hard right (for RHBH).