Traditionally I've gotten VA loans and FHA loans from local providers in the area.

I tend to see stolen light bulbs, smoke detectors, hydraulic door closers (yes), shower curtains and shower curtain rods, toilet paper spindles, medicine cabinet glass/wood shelves, window blinds, they also tend to break ceiling fans.

Once an offer is accepted, expect a 4-5 week closing period (if traditional bank loans are to be utilized).

Definitely plenty of companies out there that will handle STR - but just be aware that STR PM is more expensive than traditional. 3.

Generally there is not additional funds required to assume a loan beyond traditional closing cost but the seller would revive any proceeds above and beyond the remaining loan. 

You cannot get traditional home financing for a mobile home in a park, as it's personal property and not real property.

As @Greg Dickerson said, borrowing from a bank/traditional lender will be cheaper.

I want to build and refinance to pay back the lender and transition to a traditional mortgage which we then plan to pay off in under 10 years combining our earned income with rental income.

Can a person contribute to both a Roth and a non-deductible Traditional IRA (then convert to a Roth soon after funding) in the same year? 

Somewhere midway between hard money and traditional financing.