I think the one large dressing room is fine (but two seperate bathrooms is really nice, especially if one has a shower). Models usually aren't shy, and if you have a stylist its easier for them to work in one big room seperate from the shooting srea. If your models ARE shy, maybe design it with a large main styling room (including the makeup station), and some small changing stalls behind a curtain, like in a clothing store. I've found its easier to plan things when they can all see and hear each other easily.
It sounds like your space is similar to my old one, and many studios, in warehouse/industrial situations. These make great studios because, amoung other things, you don't have to worry about making noise, keeping strange hours, and parking. Yes, definitly keep a list of vendors, your renters will appreciate it especially if they're from out of the area. Get menus from the restaurants, it makes ordering for lunch much easier. As for renting your stuff to them, make it easy on everyone, charge a flat fee per day for what you rent. Either by the item, or say, for "lighting equipment" or "camera equipment" (bad idea BTW) or whatever. We used to include a strobe pack and three heads with a rental, anything extra was at the same rates our local pro shops charged (except they didn't have to pick it up).
Basically the more services you offer, whether included or extra, the less work your clients have to do, and the more they will appreciate your facility. And don't forget to charge a "clean-up" fee if they don't leave the place as they found it, and make sure they have trash cans available. Of course you'll want to really clean up after them (restrooms and the kitchen for example) but I've seen some pigs leave a real mess. If you have a painted floor or cove, you should charge to repaint them if they mess them up. Don't forget insurance too. Your rental clients should present you with a Certificate of Insurance naming you as a co-insured. Its either very cheap or free to them, so there's no reason why they shouldn't be able to get one if they're in business. If they are an individual hobbiest, you should check with your own insurance broker to determine your liability and build something into your rental fee. You don't want some photographer having a model do some trick that causes her to break a leg, and then come back to sue you.
Regards,
Andy Pearlman
Andy Pearlman Studio