If you are just starting out I might caution you on getting into a full gut rehab in an urban area. 

However, given that we’re both military and a couple other circumstances, we have a bit more capital than a typical young-20s couple to invest so are also looking to buy a multi family (ideally quad or tri-plex) property that we can do some light rehab on and start cash flowing.

So, most are looking for a renovated home.Yes, not everyone will like the choices made in the rehab, but they technically don't have to make any changes.

@Karen Rittenhouse is right, we can almost offer nothing because most people arent going to rehab the property themselves.

We handle other investors rehab but we are also investors ourselves.

I'm looking at some of these houses being badly/cheaply rehabbed and think : really ?

Partner with others who will do the active management (including rehab, mgt, maybe even deal sourcing).

Would it be a good idea to vet a new Gc by getting estimates on rehabbing the third floor with carpet and mainly renovating the bathroom?

I went to the address they gave and did not see them listed in the directory.

Depending on weatherThe following is the repair bid and information on the said above address.