Separate properties are generally more attractive to retail buyers, since it is a limited market interested in the live in a unit/rent out a unit if they are the same property legally. 

My current role invovles analyzing loan profitability, assesing portfolio risk and designing new process/methodology to maximize profits for my employer. i work scpecifically with mortgages, so i have seen and gain a deep understanding on how a mortgage work and the profits behind them. that said, it made me realize that if i couldn't be a lender i could probably an investor or whosaler to maximize my cash flow. i plan to be financial independant by the time i am 45. i am now 32, so i only have 13 years left the clock is thicking!

Check into it, it's very durable, easy to install and they are coming out with some very attractive wood look designs.

Don't be surprised if outside people who do illegal dumping are attracted to your dumpsters.

Many times the competing units in the area will lack that attractive detail, which can stick in the minds of prospective tenants and create a slight competitive advantage.I'd recommend exercising your own intuition to find the renovations most suited to each property and area.  

No septic design on file, common for this small NH town.

First, I recommend you concentrate on properties that YOU find attractive as an Investor, rather than trying to work out why other Buyers might like to pay you more than you Contracted, for a property that hasn't particularly appealed to the Investor-in-you in the first place.Consequently, finding a Lender who will "cover" you by lending the money to you IF you can't track down another cash Buyer before "closing" time, becomes a win-win for both Plan A (Wholesale) and Plan B (Buy)! 

If you sell you'll be looking at around 6-7% to sell with commissions and closing costs.Are you in a desirable area that will attract high-end tenants?  

I use quickbooks for accounting but feel there might be some advantages to using software designed for PM.

From a sellers prospective, You will attract every newbie wholesaler in existence.