It's going to cost you the same price other than land and possibly road surface (hard surface versus rock). 

Another consideration is gas versus electric.

I am debating between two modest properties versus one larger home.

As a TK investor myself, I have found that the criteria you use to determine who to work with are more important than the question about the single company versus multiple company aspect.Companies have different clauses in their agreements that you want to be familiar with before deciding who to work with and develop the relationship.The other aspect is the list of criteria that you put on the services you are paying for.

Regarding 15 or 30-year mortgage- If your salary is going to be $20K per year it will be difficult to qualify for either the 15 or 30-year mortgage unless you acquire a commercial building where qualifying is based on how much cash flow the building produces versus your own ability to make the monthly payment.

As a general rule, the lower the class property, the higher the rent return versus purchase price.

It’s an upfront cost (varies with market- in my market it’s around $525) but it would show you your home value versus homes recently sold.

You would probably do much better working for a competent wholesaler that has a lot of experience versus trying to learn the whole business on your own.

It will be miniscule compared to the neighborhood price comps, versus the skin of your house.As to appraisal or resale value, maybe a bit more just for the fact of having some fresh updates. 

One thing I would wager on is that it will be expensive.