I settled for a market rate tenant but for ($1000) $300 less than I anticipated but $300/mo more than the property demanded before the renovation (It was the lean winter time). 

If you assume that your fixed costs (taxes, insurance, commissions, closing costs, other holding costs, fees, inspections, etc) are about 10% of the sale price (which is generally about right for our deals), your anticipated profits on these two deals are $15K (on a $280K sale) and $30K (on a $520K sale).These margins are a bit thin, especially since those are best case numbers if you sell for your ARV.

Just like any other business you can anticipate 1-2 years of losing money or just breaking even before you have learned the lessons of running your business.

I anticipate taking the plunge in a week or two once I get my marketing in line.

He had recently spent a lot of money upgrading a couple of the units in anticipation of a sale closer to asking.In 20 days I upgraded one unit (secured early occupancy to do the work) to an immediate $750/month & it was rented before the work was completed.

Anticipated close is middle of August (they're dragging their feet on the appraisal).Your estimate looks in-line with what I saw when shopping for a loan (credit union had lower rate with points...Quicken loans was lower rate with many points)

I can use the money in my bank savings to help me purchase my next investment property in December (I won’t live there), which I anticipate will require a 20% down payment.

They currently rent for $2k combined and I'm anticipating $3100 when all units are done with renovations. 

As a new investor I overcome my fears by being extremely conservative with my numbers (by anticipating above average vacancy, maintenance and capex costs) and knowing that I have multiple exit strategies.  

Mostly, I think of what clients get frustrated with that they didn't anticipate: permit delays, ordering doors or cabinets that are on back-order and cause delays, not specifying brands of paint colors, fixtures, etc. - there is such a variety of things that we know cause delays, but seem to surprise clients.