I recommend 8-16 week cycles of SARMS followed by a 4 week mini PCT.
SARMS are only minimally suppressive of natural testosterone production so all that is needed as a mini PCT after a cycle of SARMS is a good natural testosterone booster like HCGenerate ES from n2bm.com.
After the mini PCT, you are safe to start your next cycle of SARMS.
Of course. But keep in mind you need to take breaks from sarms as well (except for MK677, you can take it for longer periods like 6 months or so).
However, the yk11 is not researched well enough so I would be careful with the sources carrying it. It might be bunk or god knows what, but myostatin inhibition is a concept not researched well enough.