For example, MEP plans are not required for permitting, but if you are designing a complicated house, having a MEP plan certainly helps to guide the trades to know exactly how and where to install the fixtures, versus something they have to figure it out impromptu in the field.

If you have experience in managing construction, then you should feel comfortable filing an Owner Builder permit.

Since your experience level (1st investment) is very limited, I'd speak with some title companies to get a feel for comfort level in working with them.You'll be asking a bunch of questions (you should!)

Can anyone suggest a market where one-bedroom STR's that are nicely designed do well?

Security deposits are used for damages and are not designed to be applied to fees or rent. 

Our compromise was to design the upstairs to be like a private in-law suite so it could be rentable on Airbnb when we choose to do so.

My issue is that I come from a low income background and have fought my *** off, pardon my language to get to where I am now and comfortable.

S8 is designed to keep certain people financially dependent and financially illiterate.

Can anyone recommend a design build company that would handle any zoning needs with the city, as well as complete the construction and leave it rent-ready for me? 

After posting I saw in your profile you are a software engineer.....What would be REALLY cool...If you could develop an easy to use Gantt chart software (Think Microsoft Project, but WAY easier to use) that was designed specifically for Real Estate reno / BRRRR.