The extent of the rehab project is dependent on many factor, including (but not limited to): Deferred maintenanceAdditional rehab costs to capture increase in rentsTarget demographicsNeighborhood dynamics (including comps)How much repairs and maintenance a building will even allow?

You don't want a year lease because people may move in and not get along with someone.How much you can charge depends on what you provide, your neighborhood, house amenities, neighborhood amenities, etc.

It depends on what you are looking for, if you don't want an agent to do any analysis or deep digging to find properties, your friends are probably capable of handling all the paperwork in a transaction just fine. 

Submetering costs really depends on what you want such as local company, automated reading, is your plumbing currently split to each unit or not, etc.

All this depends how strong you come in on the offer in the first place.

Typically rising market, property taxes, interest rates...Somewhat depends on your income level too.

Where to go for that depends on your creditworthiness and other factors (personal income/DTI), how you own the property (is it in your personal name or an LLC), when did you purchase it--less than 6 months ago?

I am still undecided on which route for funding to go, but I guess that depends on the right deal!

@Brian Kraft depending on age I use 50% to 55% on total cost to gross rent that is my rough in number.

Any profit split varies depending if your relative just gives you money or also helps you physically.