Rental Car/Taxis are available in Villahermosa and Mexico City.
You should plan around $15-$20 per day per person for your own food expenses. The most expensive places to eat are the American fast food places.
For lodging this really depends on your tastes. You can stay from around $20 per day up to $45-$120 per day. Compare prices on your local travel sites. Ask your advocate to help you book local travel to reduce the cost but ensure the place is clean, has access to sterile water (for formula, cleaning bottles, etc) and fits within your specific quality range.
Laundry service (hint – don’t use the hotels but find a local laundry service it is a fraction of the cost). Always add an extra day to the amount of days they tell you on when you get your clothes back.).
Purchase a prepaid Mexican Cellphone on your first trip (eg Telcel). This will allow you to call your clinic, doctor, surrogate, etc in Mexico for a lot less.