There is NOTHING like drawing from life. I had five or six years of almost weekly drawing from life sessions with a local artist here. He started organizing informal classes with a model (clothed, usually in dance outfit). Unfortunately, after doing this for more than 20 years, he's finally bowed out. You can get a little closer by using either videos (some free online resources on Vimeo/YouTube like https://vimeo.com/croquiscafe and https://www.youtube.com/channel/UCA9o111IH1VD8Kxz0YLn8_A) I like videos better than still photos because it forces you to act like you are in a live session. You get a lot more of a 3D feel, rather than just tracing out a still image.
Going to something like Proko.com is also hugely beneficial. They have a huge collection of videos (humorous, but right on target) both for free and some premium content for a price. They have collections of reference photos (I can email you some), and a LOT of anatomy lessons.
I'll also give my own personal bias that you still draw with more fluidity with a pencil than you do with a computer. I know people who do absolutely amazing work on the computer, but I think they first learned with a physical drawing tool. I haven't done much with charcoal (the real stuff), but it forces you to focus on the flow of the form rather than fiddly details.
Body types? Well, some of that is just keeping your eyes open and watching people, and forcing yourself to DO it. Draw lots of clumsy pictures, and eventually they start getting better. I have a pile of little scrap papers that I draw on sometimes. The fact that I know it's a throwaway drawing somehow makes me loosen up a lot!! My wife works in a print shop here, so she collects lots of fragments (eg, quarter sheet size) with slightly heavier paper, so it's better than plain old copier paper.
Hmmm... You'll have to try the Proko link again. I tried it and it seemed to work fine.
Yeah, there's a balance point where you always try to draw a "good" picture, but you're not shackled to the perfectionism of it.
(And yes, drawing/sculpting natural looking breasts is an interesting challenge... )