Hi @Vic7,
Great questions!
1. I personally think dealing with guests doing a lot of cooking is part of the cost of being a host. Some guests will cook a lot, and some won't, so you take the good with the bad. In my opinion, asking them to limit their cooking is going to be slightly awkward. If you really dislike it, then I'd suggest ruling it out altogether, and updating your house rules to reflect that.
2. As for the bathroom cleanliness, whilst the situation you've describe (wet towels and hair) is slightly gross, but it is probably in line with what you should reasonably expect to deal with as a host. These issues are just part of the good and the bad that come with hosting. If you want people to keep it very clean, it sounds like you want housemates, not guests. I agree with other commenters who said that you probably should clean the bathroom. It's not very fair on the guests if you have two separate parties who rely on each other to keep the bathroom clean, I think they are contracting with you (not each other) and could reasonably expect a clean bathroom. In my opinion, it's quite problematic that you're taking multiple guest bookings simultaneously, particularly if you're not able to provide them both with a satisfactory experience (due to the fact that they'r erelying on each other to clean the bathroom). I personally would not be happy with that kind of experience as a guest.
Regarding cleaning fees, I normally tell long term guests that their cleaning fee covers one clean (ie: it's clean when they arrive and it will be cleaned when they depart) and if they'd would like additional cleaning services, that can be organised at a cost of $50 per clean. However, if you're hosting multiple parties of guests, you're in a slightly different boat. In your situation, you could consider charging the guest multiple cleaning fees, proportionate to the number of times you need to clean up after them. I personally don't vary my cleaning fee depending length of stay, although you're entirely right that long term visits require far more cleaning effort than overnight visits.
3. Yes, I would consider charging extra for laundry if they are doing a lot. Again, I think if you include laundry in your service, you need to expect that some people will take advantage of you and do excessive amounts of laundry. But if it really bothers you, then you could increase your cost.
Good luck with your hosting!
Rosemary