As you're not in a rush, taking the time to learn, plan, and prepare will set you up for a successful and informed real estate venture. 

My question is: If the detached garage already has water and electricity (100A) set up, how much does the cost go down and from which of the three cost categories (plans, fees, construction)?

I have the funds set aside and am now contacting agents in that area.

If they all have a pool, then you should to.If they don't, then you can set yourself apart by adding one. 

I spent hours last year trying to find if the MH is officially one or two bedroom, both for advertising it and for setting any limit on the number of occupants. 

It's a way to avoid the usual loan challenges, but it comes with its own set of risks and things to understand.Now, the good and not-so-good parts of Subto:Good stuff: You might be able to buy faster without waiting for loan approvals and spend less upfront without typical down payments and closing costs.

I assume you will need an architect and engineer to get your set of plans going?

I know with traditional lending you cant do that but we did not have that kind of set up.

You can use the loan to cover the purchase price and then work on adjusting the rent to market rates to increase cash flow.

Are they just rolling with you, or are they setting the market straight for you?