The more time he can dedicate to growing his wealth bucket, the faster it will grow.If he doesn't have much time or knowledge yet, a syndication for non-accredited investors is good way to learn.He could also put that capital down on a 4-plex and househack.Or find a great partner who has the experience and can put his capital to use in harmony with your friend's investing goals The other options you listed seem too risky if he doesn't have much experience.Good luck 

Leverage allows you to scale faster while your tenants pay down the remaining balance.

I have had a few minor issues during the first lease year, but found the faster you respond to these situations the happier your tenants will be.

FYI, new back splash is pretty, but occupant comfort will be worth its weight in gold, when you’re not receiving calls on a Sunday about the AC.

PLUS in my mind a well seasoned very close relationship with a local community bank that is funding you is worth its weight in gold.. in the event of a water landing you have a much better chance of restructure with them than you would with the big funds out there and HML for sure.  ..

Could you get something from code enforcement which would carry more weight and try and stay out of the middle of this?

Can I engage multiple agents to get it rented out faster.

BUT if your aim is to have passive income from real estate by having many doors/ many tenants paying you rent then why not scale it up faster by buying few doors in one deal? 

They will get the job started much faster, they are juggling less projects (you might be his only project!)

Ah, the hellhole of Massachusetts for being a landlord...Yes, it is going to be your word against hers, but the fact that you live there is going to add to ton of weight to your side if she says the other person doesn't live there.