If you're looking to aggressively grow your portfolio, then I would put as little down as possible (hoping that you're not planning on living off the rental income any time soon). 

If you take the rewards in cash back you need to claim it as income.

I am seeking to purchase BRRRR properties for long term investments as well as fix and flip opportunities for additional income in Brevard County.

If however, that 30% is largely income you have earned above your base contribution that is another consideration.At some point, you will have to take out funds from your qualified retirement plans and be taxed on it.  

I work in Construction Project Management and have found that way more people than I think have found an avenue into RE that has been supplemental income and even a hobby for them depending upon which route they took.

Say your firm splits 50/50 with you (there will be some variation of the split it could be as much as 80/20 or 70/30) but that $12,000 comes into the firm and say you get 50%, so your taxable income on the transaction is $6,000. 

The suburbs will be higher taxes but generally better schools and higher income tenants.

I was thinking I would reinvest some of the rental income to make some minor repairs/maintenance around the home.

If you want to be retired and have passive income, then investing into real estate syndications, debt funds, oil and gas companies, hard money lending, etc are good options.

When dealing with two separate houses on the same lot being sold together, it is important to consider several factors in determining how to calculate potential rental income.