I've got a few questions regarding stretching

First: when I stretch my penis usually my foreskin goes back on the gland partially, so I almost have to grab almost the base of my unit to avoid it from happening, is it ok? (I steel feel pressure on the pelvic bone).

Second: If I stretch with a slight erection, like 20/30% is it going to be dangerous or make it hard to gain? Cause I find it almost impossible to not get atleast 20/30% erection