I'm looking to do a majority of the work with friends who work in the trades in our spare time.

If not, you could also rent out a spare bedroom in your unit on a nightly basis on Airbnb.com for a few nights a month. 

What you described above is the most common way folks get started simply because their time is something they can spare while money may be something they cannot at the moment.

I'm an agent with a lady and her baby and you cannot refuse renting your room to a lady with a child and by the way the bed in one room would have to go in storage from the looks of the pic to make room for the baby's crib, walker, etc.Usually the calls go on with the caller repeating their scripted quotes and how refusal to show them our room will result in visits from 'officials' and charges filed etc.. all within a total call duration of just 1-2 mins or so (while we reiterate we're not okay with co-ed bathrooming in our household, nor making modications as we're probably relocating after graduation).Of course, we are compassionate about persons with disabilities but since when did offering a spare room or two in our own household turn into some sort of implied legal 'boxing ring' climate?

Put every spare dollar,nickel and dime on your mortgage and pay it down as quick as possible. 

Using my current skills, Marketing, database, customer service, writing etc... what could I do in my spare time to add value to other investors who are building their business?

You could buy a Fourplex, rent out the additional units and even rent out any spare bedrooms in the unit you are living if you are in a position to do that.

This can also be applied to SFH's by renting out the spare bedrooms, but that's less common.

Another option is combi-boilers which are gas fired and provide both your heating and hot water in a compact unit located in your boiler room.

But as soon as I can get some spare time, I am going to mount it myself.