botox business

I am a ICU rn in Az and am interested in pursuing a career in aesthetics. I'm not quite sure how to go about it and have some questions for any of you with experience in this arena.

would it be better to take the individual courses to inject botox, fillers, etc. or would it be more beneficial to become a licensed aesthetician?

As far as working goes, do dermatologists/plastic surgeons typically hire rn's for this, it seems to me like they prefer aestheticians because they can pay them less. what about "renting space" from a doctor (like a hairstylist or nail tech does) and what kind of insurance coverage do you need if you're an independent contractor?

Does anyone have ballpark figures for start-up costs for opening a med-spa (I live in phx, AZ)

thanks!!