Im not an expert in all these subjects....... I have my drone business and fly drones for a living for another company doing infrastructure inspections. We have a huge fleet of drones and I have experience with most of them. First off my personal drones started as a Mavic mini, I them bought a Mavic Enterprise dual and then an Inspire V1 Pro. The only inspire that can carry an IR payload is the inspire 1. The batteries are getting old and are no longer made. The flight time is short and you will have to fly that bird more them the rest. The Matrice series are nice, but it is way overkill on anything that you have marked on your list. I sold my Mavic Enterprise and I am looking to upgrade to a M200 soon. I picked up a MA2 to fill the gap in the short term. The inspire 2 is a nice bird for Cinema and stills but Expensive and no capability for thermal payloads. The Parrot ANIFA USA has my attention as does the Mavic Enterprise Advanced. There is no money in S&R so dont invest in it. Having done a couple of SAR missions, unless the subject is in the wide open it does not work well. Very much a tool but not the swiss army knife for sure. Keep in mind some restrictions are being put on DJI drones, and soon operation of one around critical infrastructure is going to be difficult at best. We are currently on a deadline at work. In 3 months we can no longer fly DJI drones and are trying to find a solution that has the same capabilities as the Z30 camera. Its old tech but works well, and there is not a lot out there. That may change in the future but the reality is as of right now, DJI has had some bad publicity, and Critical Infrastructure and federal monies will prohibit DJI products in the near future. I hope that changes.
There is not much money in real estate unless you have a huge client list. Real estate sounds like a great market to be in, but it seems to be a race to the bottom as far as money goes. I have friends in Real estate and still cannot break into the Market. I could get some jobs if I wanted to do jobs for 25-50 dollars after a 1 hour drive! Personally I would use what you have and try to build your business. Jumping all in without building your clients will do nothing but frustrate you and cost you money. Work on a business plan, and do some test mapping jobs, fly every chance you get to find out what is going to make you the most money. If you enjoy flying you will enjoy all aspects. It is easy to get wrapped up in being a 1 stop solution for your drone business, the reality is a small guy starting off it is too cost prohibited to do that if there is not a revenue stream to overcome that.
Start slow and work your way up. I prefer to buy software rather then pay for services. You will need photo editing software, Video editing can be found for free like Davinci Resolve. Mapping Orthomosaics are expensive, I purchased Agrisoft Metashape since it was affordable and provides good results. You need to hone skills and practice. I am gearing towards Infrastructure since I have the training and experience in that. My current job is not going to last forever so I am trying to gear up in case something happens I can make a shift.
Just my advice.