I know speaking with contractors is the most efficient way to get accurate costs but it is too preliminary to do so.Any websites, softwares, books, etc to find some general costs that I can base off of?

Make sure your ARV lands in the biggest pool of buyers so you have the highest chance of exiting your project, efficiently and effectively.

What are some recommendations moving forward to maximize the efficiency of the rehab to get the property ready for prime buying season?

The majority of great deals I've found, the majority of the capital I've raised, and the reason I have been able to be so efficient with my work is because I have spent much of my time forming life long relationships.2.

A couple of tips - you may have thought of this already...1) An architect can help you with both the fire wall issue, and the efficiency ratio (IE: how much is actually rentable vs how much goes to corridors, etc) Totally worth it if you can increase your efficiency ratio.2) Contact your local utility company to see about engineering assistance and/or $ assistance for installing new lighting and/or HVAC.

That’s cost efficient.

All appliances ($10000),  New HVAC x 4 - as old furnaces used for church are not efficient and were huge.  ($18500). 

This would create an allocation schedule that would compensate the managing members in a tax efficient manner.

@Sunil Kumar The mini-splits tend to have a much higher SEER rating (more energy efficient) than traditional units so they should be less expensive to operate. 

I have found that routing everything through a gmail account with a google voice number connected to google hang out allows me to be very efficient.