A reputable GC should have accounts with all vendors so there shouldn't be any upfront money needed. 

It is unlikely to cover all the kinds of disputes that you are going to run into down the line, whether that be issues with your vendors, your clients, etc.

I also have connections with many vendors should you need special services for flips or prepping a rental.

I have “vendors”, contractors HVAC, etc all lined up as we are flippers too.

We have a few we use that have gone through our vendor approval process (properly licensed and insured).

In fact, this unit is what kept most folks passing on the building and it enabled us to present the vendors with a lower offer and convince them it wasn't low enough.The tenants had been there seven years before we bought the property and the unit was already in a condition where it could not be relet.  

In the day time, it is nice to walk around and look at what some of the vendors offer.

Great networking event and a good selection of vendors in the vendor hall.

Realistically, you'll need someone who is consistently able to visit the property to inspect after check outs, coordinate cleaners and other vendors, etc.

On the plus side, you are close enough to drive by the property, see if the PM's vendors and keeping it up, etc.