If you run 250 mg per week of Sustanon then you may simply increase the dosage. You may go for Test E + Sustanon, but there's no benefits as long as dosage is the same, you're only going to have 2 pins instead of 1
Yes. Unless you are on TRT or cruising. As for cycle - 16 weeks. And recommended for as long only if you have previusly used test for 12-14 weeks experience and everything was fine.