If you can buy and hold, you will make money in the next 3-5 years, even though you may have a temporary negative equity experence. 

Big money grab from the city.

(Instead of complicated private money or hard lenders)

I want to move to a single family (maybe build the house) but I don't have a ton of money saved (only 15k) because most of my money has been going into fixing it up.

Does it make sense to offer an additional bonus (let's say 5K) if they are able to negotiate for $1.1MM on top of the usual 2.5% - 3%?

With no equity and negative cash flow from the get-go, I'd say if you want a hole to throw money into, get yourself a nice boat. 

Instead, invest in areas with a higher ROI, like backyard amenities, game rooms, and standout design.Most of our clients refresh these spaces with a new coat of cabinet paint, updated flooring, and small changes that make a big impact.

I have $70K of my own money I can use as a down-payment, but am looking for someone to finance the rest ($280K) as I'm a real estate agent and am having difficulty securing a loan from a traditional bank in a timely matter.

It’s more of a benefit to the tenants than a money maker.

Getting in the trenches not only is the best way to learn, but you'll be on the fast track to make the connections you need (contractors/vendors).