I think if your friend is willing, then it sounds like it could all work out really well for all of you. It sounds like a good fit.
I'd suggest though, doing some kind of professional counselling (as you've already mentioned) to set out some kind of contract or guidelines. Because even though your friend would be the donor at this stage, once the child is born, things could change.
I know a lesbian couple that went with a known donor about 8 years ago, it all was worked out before hand and seemed amicable. I think it was sort of a home job, so not sure what legal papers they signed or agreed on. When their little girl was born, he fell in love with her and couldn't help wanting to have a more fatherly role. It didn't help that she looked like a duplicate of him. I don't think he expected to feel it so strongly and it ended up getting a bit stressful because he wanted access to her. They couple now basically co-parent the child with him and it has all worked out really well, but it wasn't what they were expecting in the beginning. It was all a bit sad because i don't think he even anticipated he would love this child so much from the beginning, he just thought the would be an occasional person in her life but once he saw her, he instantly fell in love with her.
So i'm just saying, get all the legalities worked out before you go ahead, so you can prepare for all eventualities.
Absolute best of luck to you! Hope you end up with a beautiful baby soon.