If I was going to use my Mavic to assist realtors, home inspectors...ect, do I have to register it for commercial activity, and take a test? also, what do people normally charge for this kind of service.
Yes if you do any commercial work were a person or company profits from it you have to get your part 107 even if you do it for free you still have to get it.
Just to add for any others like me in Australia, no licence required down here as it is less than 2kg. However you do need to apply for an ARN from CASA then apply to CASA for a permit to fly for hire or reward min 5 days before you first do. Only takes a few minutes for the ARN application and you get your number back in a day or so, then another couple of minutes for the permit application and in 5 days you are good to go. No fees and the permit is good for 12 months.