What do you think they will be doing as a STR?

It is good to know the area, but I think you are focusing on the wrong thing if that is your primary focus.

Why do you think purchase contracts are so long and have such small print?

The cost of land generally includes the cost of clearing, grading, planting, and landscaping.Land preparation costs, such as landscaping are depreciable Certain improvements made directly to land or added to it (such as shrubbery, fences, roads, sidewalks, and bridges) are generally depreciated over 15 yearsKeep in mind that depreciable rental property costs with a useful life of 20 year or less may be eligible for bonus depreciation.I don’t think the sources that you found are accurate since some of the improvements you mentioned can be depreciated and over a shorter period of time.

Long term I think things will shake out. 

North Broward Area (Undergoing Gentrification)Type: Triplex Units: Two /1-bedroom units Current Rent: $1,500 per unit, month-to-month leases Tenant Quality: Great tenants, familiar with the neighborhood, payments made regularly with sufficient funds Potential Rent Increase: Neighborhood improvements and upcoming developments suggest potential rental rates could rise to $1,800 - $2,200 within the next two years Upcoming Development: A new $2.2 million road is being constructed in the cityCurrent Market Value: $680,000Current Cash Flow: $1,500 per unit, 3 units totaling $4,500 per month Condition: Needs some work Price: $435 ,000This property is a prime investment opportunity in an area poised for significant growth and appreciation.What do you think?

I would get at least 3 estimates and I don't know your market, but I would think one of the plumbing companies would have access to give you financing.  

I think there are a few private money lenders in our group including myself, people are always needing funds, and there's a few wholesalers that also are passing deals around.

The agent we are working with would like to list it at $1,300,000 OR I think we could rent it out for $5000-$6000/mo. 

I've been thinking of purchasing a lot to build a 3 unit building made out of shipping containers.