As for the electricity, the units are separately metered so the upstairs tenant will pay for his own and I will be splitting the bottom unit's bill with my roommate.

I called the listing agent to get the details: Home has two, 1 Bed/1 Bath apartments (upstairs and downstairs) with separate entries.

I called the listing agent to get the details: Home has two, 1 Bed/1 Bath apartments (upstairs and downstairs) with separate entries.

If you want to isolate performance down to each rental, you can set them up as separate entities and track income and expenses for each.

If I go to Home Depot and spend $500 on a new bathtub, a door, paper-towels, a new screwdriver set, windex, and valve stems for a faucet; would I break these down into supplies, cleaning and maintenance, and repair with separate entries?

Having two separate companies trying to manage and run the same job (at this scale) doesnt make any sense.  

I've considered running two separate investors groups-one just for fix/flip and the other for rental units.  

And Rehab Costs would be the cost to tear down and construct the new property, including all hard and soft costs that aren't factored into the Fixed Costs.For example, if I have a house that I can tear down and rebuild a 2000 sf property that would sell for $400K; it would cost $100/sf to tear down and rebuild; I'd have $50K in Fixed Costs; and I'd want a 20% profit on the resale price ($80K), my max purchase price for the tear down would be:MPP = $400K - $50K - $80K - $200K = $70KKeep in mind that the rehab costs must account for all of the following:- Site Planning- Zoning Approvals- Utility Installation- Permits/Impact Fees- Environmental Studies- Etc...If these costs aren't factored into the per-square-foot construction costs, you need to factor them in separately. 

Also, if I plan to invest some of my own money, and I want to get pre approved, are there separate pre-approval processes for buying an investment property (multifamily) vs a single family home?

Pull up Homeaway, Airbnb and flipkey in separate tabs on your computer, put them all on map function and zoom in on your target (Seaside heights) then pull up the MLS (realtor.com) same map function.