1) You should get in the habit of using both imo depending on the fight and whats going on. Like levi ex i'll start with a F3 > T2 > F1 1kmp >sc/flare, because thats all i can fit before levi goes under. Starting with F3 gives a faster burst of damage than B3 does.

But i have a few reasons why i start with B3 over F3. Starting with B3 means less aggy at the start of the fight, a free thunder 2 and a longer fire1 rotation. And im only 1 fire behind the guy starting with F3.

2) someone posted this in another topic which i never knew you could do until about 3 days ago O,o but what you can do is keybind /face target and just press it whenever you think you might get interrupted.