This will give you the hands down most valuable skill in RE which is sourcing good deals.

But a good skilled worker, whether GC or sub's, can be invaluable.With all that said, to try and save money, I would see if you can find a good home inspector referral, many of them are or were GC's themselves, and pay them to check out important work that you have done.

To be honest (as a business owner myself) I have been surprised by the professionalism and communication skills of these lenders. 

This speed can create unrealistic expectations for clients about the time it takes to close a deal, subsequently putting pressure on realtors to hasten processes that traditionally need more time for due diligence.Client RelationsRealtors invest considerable time in building client relationships, providing advice, market analysis, and negotiation skills.

If you continue to own and manage this or other properties, you will find that tenant selection is one of the most important skills you must do well in order to succeed. 

It's also highly subjective based on the lists you're dialing and your sales skills.

But, the real challenge and skill, is in recognizing future opportunity today, or creating it with value-add opportunities.

You have to turn on possibly a new skill of protecting your new found assets.  

I have a 3rd LLC (non retirement) created in NV, working on buying RE in Detroit, MI. once the purchase has consummated, I file the foreign LLC filing with MI state, do i need to file for FINCEN too??

Its more of art form and dependent on skill.