All Star Plumbing, Eloy Jimenez, and Benji Molkzyk all helped with elements of the rehab and their work was beyond amazing.

Best option was buying something at the grocery store and heating it up in my hotel room microwave. 

Is it worth it to be involved in all the little things like selecting fixtures, tiles, heating units, or do you generally go with what your GC recommends?

There is a cost benefit there... look to those key elements.

The market is way over heated.

One is more of a workshop (half bath not full) but it is heated and 1994 sq ft. so was denied for a Freddie Mac conventional loan.

Depending on what price point you're looking the market is heating up and 90% is not going to be that attractive.

Our plan is to BRRRR the property but cash is going to be the one element holding us back. 

Install register cover on heat vent in the main roomb.

If you know the exact property, did you get the average costs for heating/cooling, internet, etc etc.Like @John Underwood said, take all the info and plug it into a spreadsheet to get the best idea of what to expect.