My dad, brother and I combined our cash for $103,000 towards the purchase and closing amounts of $271,000.

It seems you are combining the idea of the tenant-buyer (TB) giving you money to go and buy a house to RTO to them?   

The compounding effect shouldn't be discounted and there would be nothing to stop you combining strategies by paying off one or more properties to 'cash in' the gain in asset price to reduce your borrowing on one or more of the remaining. 

Combined the financing side equals,...

I would like to start working for Marcus & Millichap Raleigh office (if anyone has a contact I would really appreciate it)My assets include about 200k (cash, equity, and investments combined) an excellent credit score, and a few investors that have not given a specific amount (one investor owns a trucking company and wants to diversify).

As long as the LLC's have common ownership, they can be combined under a single Umbrella.A higher Personal Umbrella would not hurt, but keep in mind that a Personal Umbrella would need to list the LLC on the policy for the LLC to be covered by the Personal Umbrella. 

If they can't insure it try contacting several Independent Agents in your state to see if they can cover it under a Homeowners or some combination of policies. 

Also, if you combine the strategy of adding value with this house hack, you can then gain equity faster.

I would NOT combine water/sewer with trash.

Is there any difference in loan options or insurance for buying something with a commercial unit before I combine the 1st floor?