I would suggest you get a trusted GC to give you a close estimated repair cost for a rental or sale. 

A good chunk of items will have to be estimate/not exact because they don’t know what cabinets, flooring, light fixtures you’re using so there’s now way to be penny-precise on that but they should have some pretty good estimates as to what granite countertops, flooring, cabinets are going to cost you.

But it can be good to give an estimate, IF you can provide figures that are at least close.

4) I can assess a property and the cost for repairs if I can have access to the property, however, how are the repair costs estimated when access to the property is not granted?

I need an FHA approved Contractor to do a walkthrough of the property with agent and me, to get an estimate.

Only a lender can really give you the number, but as long as you know it is there you should be able to estimate. 

thanks @Matthew Rolf, I contacted acosta plumbing as well. got an estimate. will contact more and post update here.

See my latest BRR   https://www.biggerpockets.com/forums/223/topics/61...The 50% expense rule is not a high estimate if you have a PM. 

I am very tempted to have a contractor come in and give me an estimate on the rest of the work for me.

Are there any ball park estimates for rehabs you guys use?