a caregiver can have 5 patients in addition to himself so tech you are able to grow for 6 people total.
Not alot of people like to be caregivers atm due to the fact that you have to register your grow and allow inspections.
When i first registered as a caregiver there was no additional expense but i did not renew as a caregiver when they changed the rules so i dont know if they added a fee to it at this time.