no, it will be a single family residence purchase with new construction for additional units on the lot. 

Interest rates.In order to provide good advice, we need good numbers.

(other than having cash/equivalent, preliminary title report, and the appropriate deed ready to go 'on hand')The MOST difficult part of this will be getting the lender to provide you with the reinstatement figure to bring the loan current (I do this and take title sub-to because it's actually easier to get the lender to provide a reinstatement than a full payoff). 

For the railing height, I'd find a local carpenter to ask about completely removing the railing and balusters and doweling in an additional length on them.

Meanwhile at the other end of the spectrum there are turn-key providers who specialise in new-construction.

Additionally, what if I sell the extra lot to an owner occupant and rent out my units.  

From evaluating a potential deal to providing insight to rehab steps.

The problem is that the tenants came with the investment property and while I have a lease with their names signed, I do have any additional info like their SS# or Driver's licence#.  

Additionally, am I required to provide a copy of the ledger to substantiate these deductions?

This is something I am happy to provide to my clients.