Cap rates look great, crime is low, and the city itself seems to be booming as of late. 

I am looking to get into 6-12 units and I find Leominster ( or Worcester ) generally financially attractive.I don’t, however, have any experience in that market in terms of rental outlooks, neighborhoods, Vacancies, help, management companies, snow removals etc..I have looked at many More affordable areas including Lynn, Lowell, City of Worcester - but I find myself somehow pulled towards Leominster.

Why wouldn't you register a fictitious business name (or multiple names) in the city the property is in? 

Looking for a Realestate agent who knows market very well in New York looking to buy a investment property that can be flipped

some cities/states offer down payment assistance programs.

The main risk is that the city might make you demolish the improvements. 

In my opinion this sounds like a substantial investment, and there are plenty of solid multi-family renters in the following markets:DearbornDearborn Heights Melvindale Westland& other cities immediately North, East, or West, of Detroit You're spot on about renters paying less for a duplex over a SFH but as you progress in the multi-family market you'll notice the differences aren't much if you choose the right property, construction finishes/overhead, tenant screening processes. 

Any advice on CITIES for buying multifamily building for buy and hold purpose?  

I see people post no deals , all deals are dried up, too much competition not like people know all the houses in all cities/neighborhoods in their state.

A flipper friend of mine bought a 3 family near long island city for 800k in 2015, it is now worth 2 million.