After 20 years in both Real Estate Finance and Contracting we are just getting started in Real Estate Investment. 

FYI I just confirmation back from Eliot Bencuya at Streitwise that they do only have 1 property now "and that concentration is a risk, we are currently actively pursuing additional properties and do intend on acquiring, over time, a diversified portfolio of quality office properties". 

We are really excited our 1st investment property, a vacation rental in Ocean City, Maryland, is going so well this year we will have a chunk of change to put into a second investment property this fall/winter!

We want to go for another real-estate investment (we are doing buy and hold..buy low, renovate and make them short term rentals on airbnb in Ocean City, Maryland).

He doesn't have a vast amount of knowledge but definitely more than us.We know a few things have gone wrong in his flips, therefore he can teach us the basic of Do's and Don'ts.My wife and I would like for him to team up with us by providing knowledge.He would not have to do the hands on but just guide us through the process step by step, we are willing to put in the work.What percent should I offer from my ROI?

If you are driving distance from a major city (or major cities like we are -- LA and SD), you'll have a better chance with a high bedroom count home. 

We are considering to hire a  reliable leasing agent at least for tenant screening, house showing and ect.

We are looking at self-managing so that should help with expenses.  

@Kyle Miller there are some that are really changing the game and as others have said they often operate at a loss to gain market share, but with Technology changing, we are going to see changes in the space.

LOL, we are on the same Wave-Length, I am confident we will get a good response.