I've been doing my soft tissue work consistently for years now so what I do is probably not going to be so helpful for you.
I don't injure myself with soft tissue work anymore but I need to remember that I used to quite a lot. It is hard to learn where the fine line is between helpful hurt and hurt, sometimes. And hard to figure when an area needs to be left to recover, and when it stands to profit from more focused work.
Increase it slowly, yes. I think the focused tissue work (especially the techniques that involve trying to force things to release) actually damages tissue. Like how weight training damages tissue. Both of those take time to recover from. I used to be skeptical... But I've come to learn the value of the gentler techniques for avoiding / preventing injury. Wider sweeping gentler rolling to help promote blood flow etc. I don't know that it is possible to do too much of that (unless it is at the expense of other things).
If your efforts to increase your rotation have resulted in your having more ROM then the muscles will be working differently. You should feel that, yeah. I like to do the release before doing the exercises that increase the ROM. I've been particularly inspired by ballet turn-out lately so have been looking into that. No knee injuries when rotation comes from the hip... Knee injuries when turnout is forced beyond what the muscles / tendons / or perhaps even joint capsule of the hip allow... I find the pinning the muscle down then moving through ROM technique gives me instant mobility for whatever it is that I do after. Luck.