No problem @Robin_Dickinson! I'll do what I can here (warning, long post!)...
Payment: We are a little unique in that she was a full partner from the beginning (full disclosure - our lead physician's daughter, but only because she's excellent at therapy). She does much more than just mental health counseling with us (helps with business strategy, some HR issues, and much more), so we pay her a salary as an owner / MHC, plus she receives dividends as an owner.
If someone was considering making the jump into paying a MHC as an employee, I would consider trying to hire a new-to-the-area MHC who is looking for clients and pay them on a per-visit basis. They should end up thanking you for not having to do any paperwork other than charting!
Availability: When we first opened, she was full time, and we did several 'soft' hand-offs - basically a 5 minute greeting in the exam room if our physician recommended counseling (which was brilliant). We do less of that now, because she is part time and a little less available for those soft hand-offs, but we'll do them when available.
Ultimately we are seeing several people that would never have stepped foot into any other MHC office, simply because there are too many barriers. This is very similar to DPC in general - we end up seeing patients much sooner than in the 'normal' system because we're so accessible! We also have very few barriers - they're scheduling with the same front office ladies, coming to the same office, and have no additional costs (at first - see below).
Our Pitch: We always mention this benefit in our seminars, and when people are either signing up for membership or considering. We say something like... "we also offer mental health counseling as part of our membership benefits, because we all go through tough times in life, times of grief, have a boss we can't get along with, or many other life issues where we could use to talk with a professional. We want to take care of the whole person, and having someone listen to our hard times is a key part of that in our minds."
Usage: Right now, we have almost 900 members and our MHC has around 30 appointments per month, and averages between 3-8 new intakes per month. The average number of appointments is probably around 6, but that's taking out the few people that she's seen for a couple years now.
We include 12 sessions for free, and then charge a $30 office visit charge after that. We honestly use the 12 visits because we think most real therapy needs about that many sessions. The $30 office visit charge is mainly to keep people honest.
Regulations / Malpractice / Relationship: There are no regulations (in Washington State, at least) of hiring a MHC in our practice directly. Malpractice actually does not cost us any extra, as she counts as an ancillary underneath our physician's malpractice.
Again, our MHC is a partner in the business, so we're a bit different. It should be easy to consider one a contractor if you hire them part-time and they're already practicing outside of your clinic. The employee / contractor distinction is more of an IRS issue, where as a contractor they technically have to be doing similar work apart from working with you.
I hope that's a helpful start!