The cost is going to be less than 30k because I will build it myself but obviously the county won't just accept my "random" estimate, they will allow to estimate $123/SF of conditioned space and $22/SF of deck.The floor plan I was planning on building is coming at $37,404 (288 SF floor plan, 90 SF front deck), so my question is : shall I make it smaller to get below that 30k limit ?

I enjoy STR's and it allows me to pay off the mortgage quickly or invest in another property with the generated revenue.

Those additional costs, like any business, will be done to generate profit.There is a nature conflict of interest when they have in-house services.  

Lead generation is a long play.

Lead generation service is different because an agent pays lead generators without any direct coupling of the payment to closing (but with an understanding that if the leads are nonsense it'll put an early end to the relationship).It's this situation that gave rise to wholesaling, because ultimately a wholesaler is doing that same deal-finding service, but they get around the licensing requirement by buying the property for themselves with an assignment clause, and then resell it to an investor at a premium that ends up like a fee but officially is counted as equity gains on a real estate transaction in their own name.

I guess I'd even consider marketing it has a one-bedroom with an office, but my guess is renting it as a two bedroom would generate more revenue.

Many business owners create plans before income is generated or before taxes are filed.

And so I sent her a random Pennsylvania license from Google search results and she still pressed me to send mine. 

After tax cash-flow generated on a $1 million property is usually 6% to 10% of the properties purchase price...$60k to $100k.

I know the different in mortgage and expected rent is about 450$ and I know I need to put aside a decent percentage of that for repairs, vacancies, cap ext, etc...Basically, I'd like some suggestions on how ya'll would keep tabs (numbers, metrics, etc) on this property to ensure that it generates positive cash flow and doesn't turn into a money suck.Thanks in Advance, Charlie