I'm a bit concerned with the values in Boston proper, and wouldn't want to take on really long projects in case the market shifts. 

These will help you get up and going to learn all the legalities as well as proper process for finding great tenants.We also used cozy.co for finding our tenants. 

I have clients who would be at 40% or 44% with just their primary home and day-job, but between all the rental income their mortgage calculated DTI, calculated properly by folks that know what they are doing, is down in the 20s, 27% or whatever (24% to 29% is a range I see again and again, for whatever reason, possibly a result of people trying to follow the "1% rule"). 

It just depends on what you need and whether or not you know enough to take care of your private lender properly.

Also, there is a difference between working and working properly.

.), security (cameras, noise detection, security policies, etc), cleaning and upkeep would be provided by me and my company for the duration of the lease.

You are moving too fast to buy and this is how people get themselves into terrible deals without proper representation.

Make sure that the water heaters are vented properly. 

If you are not experienced with real estate contracts in Canada, here is my advice...You should be working with a lawyer to have contract of purchase and sale paperwork drawn up properly (or at least review to make sure you are not putting yourself in an unfavourable situation) and have a template for going forward or be working with a realtor.

We jumped into investing with our first property without the proper knowledge.