by Howard Miller.
Short answer - yes - but the Devil is of course in the detail. You probably need to do a quick install of Moodle and try these things for yourself.
Separate logins is a requirement but I'm not sure what you mean by file/web space. Moodle has things like blogs and wikis which may do what you need.
The PayPal module is very simple and can only sell one Moodle Course at a time (will your lessons be the equivalent of a Moodle Course).
There are various ways of controlling the release of materials. See Site administration > Advanced. However, you'll need to establish if they do exactly what you want.
Anticipating somebody with a much more detailed answer, but hopefully this helps a bit