Food is good for building mass.
Anything in the gym short of frying your CNS in the long run will yield gains, though results with vary of course.
If you enjoy supersets go for it. They're useful for finishing workouts faster. They're also a good way to provide new stimulus if you're not used to them.
Personally, I wouldn't superset any major compound lifts where form is easily broken by fatigue: deadlifts, sqauats, cleans, bent-over rows, pullups, military press, and bench. If it's a once in a while thing maybe, but I'd only superset accessory exercises. For instance, an example horizontal push/pull session using this principle:
Bench: 5 x 5
Bent-Over Rows: 5 x 5 -----------> superset these every 4 sessions
Bar Dips: 3 x 8 -- supersetted -- Supine Rows: 3 x 8
Incline DB Chest Press: 2-3 x 12 -- supersetted -- DB Bench Rows: 2-3 x 12
With bench, rows, military press, and pullups you could argue the form is simple enough to superset them, but definitely avoid supersetting squats, deadlifts, and cleans -- at least in my opinion. They're too technical to mix up with intentional fatigue. You need full focus and strength on those lifts.