1) its a fakie back tail. That’s just what everybody calls them, don’t get too technical, just know everybody calls them fakie back tails and move on knowing the proper term to use if you want people to know what you mean
2) I’ve given these tips before somewhere on this board about sliding tailslides and swear they work: don’t lean back on top of your body, get on it with your body set like you are sitting in an invisible chair, knees bent, body over your thighs behind them.
Ankles are key: make sure you have them open, like your foot and shin should make an obtuse angle.
Do both of those things and you’ll find they slide like a dream