Yes I think estimating 5% would be a good start and then once you know the school district you can get a better idea of what to expect.

If yes then what should his/her credentials should be and "approximate" cost?

It’s always a good idea to consult a local real estate attorney and title company for more accurate estimates in your area.

This was very hard and time consuming, but I'm on the other side of the permitting process and ready to build.I am estimating the 6 cabins will be about 900k to build and will be worth 2x that when built.

During your initial walkthrough, inspect the property for any major issues such as structural damage, roofing problems, plumbing, and electrical concerns, while documenting all cosmetic and functional issues with detailed photos and notes.Once you confirm the property’s potential, finalize your ARV and calculate the repair costs using either a reliable estimator or insights from contractors.

Quote from @Roger Garner:Multiple estimates and get some photos of their work too.

We typically estimate standard costs for these items but get them done much cheaper with our own crew.

Prosper will yield me approximately $313/month for 36 months yielding total payout of $11,281. 

Our property management company wants to sell 3 apartment blocks for us approximate value 2m maybe slightly more, can we ask them to accept 4% sales commission?

Make sure you are using the estimated taxes shown at the Stark auditors site to check on them for next year as there are some significant increases coming!