Asking about their LTC, LTV, point system, draw system, rates, and other details that let them know you're knowledgeable about their business will probably give them more faith you're asking the right questions in your own business.

It has an evaporated air system currently and I was considering putting in a mini split ac system.

Private or community well and septic system.  

I cannot find a way to test the well and septic system because there is no power and have no history on the systems (except for a permit that was pulled in mid 1980s). 

The low downpayment primary residence loans certainly have their appeal, but by using them to shortcut the system it will complicate tax filings, tax benefits, and how you cut up the proceeds when you go to sell the property.

I was trying to do a fire alarm system like I had in the 4plex I recently sold to buy these properties, but the electrician said we wouldn't be able to pull the permits considering the cards at the Building Department had it as a 3 family. 

My partner and I are looking to buy a piece of land in North County and put a manufactured/modular home on it as our primary residence.

You can evict a bad tenant and fix or repair an HVAC system that breaks.

Do you know what type of ordering system you will need/how will you get supplies? 

To determine the STC i need to know the floor system.