IF YOU ARE WORRIED ABOUT YOUR FORM, THEN ASK FOR HELP
NEVER DO DEADLIFTS OR SQUATS WITH A BENT BACK OR IF YOU ARE INJURED
The letter on exercise order tells you what order to do the exercise. So the A superset is first and you will do A1 before A2
Tempo:
The First number (as in 2010) is the amount of time you should take to perform the Eccentric portion, or, the lowering of the weight or exercise.
The Third number (as in 2010) is the amount of time you should take to perform the Concentric portion or the raising of the exercise or weight. An X indicates as fast as possible, i.e. explosive (but still maintaining good form).
The Second number (as in 2010) is the amount of time to hold the weight/pause at the bottom of the exercise.
The Fourth number (as in 2010) is the amount of time to hold the weight/pause at the top of the exercise.
Using 2010, you would perform a 2 second eccentric portion (lowering the weight), no pause at the bottom, a one second concentric portion and no pause at the top.