Boston allows STRs in owner-occupied buildings only: https://www.boston.gov/departments/inspectional-services/short-term-rentals

Your intention is that you will occupy the property at some point during that first years. 

The easiest way to avoid the licensing issues is to simply lend money, or buy paper on investment properties. 90% of the states do not require a license to originate, lend, or buy and sell paper if the subject property is Non Owner Occupied, ie: Business Purpose Real Estate, ie Investment Property. 

I don’t have months and months of rental income but I’m now forecasted to make I believe part of the requirement for the loan was that you occupy the property for the first year.

You cannot buy a property as a "primary residence" unless you plan on occupying the property within 60 days of closing, and it sounds like you may not be able to make that happen. 

The Fair Housing Act may not apply to the following types of housing in some cases:Owner-occupied buildings with no more than four units,Single-family housing sold or rented without the use of a broker, andHousing operated by organizations and private clubs that limit occupancy to members.Again, talk to HUD and see if you are exempt, then you can put this entire issue to bed.

Capex is separate from ordinary maintenance.There are also considerations when buying an occupied rental.

@Jaekwan Lee see copy & paste below:Purchase Agreement Clauses for Buying Tenant-Occupied Rental If you’re considering buying a tenant occupied rental property, there are some documents you want to acquire for review prior tothe closing.

I am looking to move into the top unit occupying 1 bed, and looking to furnish the other 3 bedrooms and purpose sharing the one bathroom, with a midterm tenants.

As for the loans, you can benefit from owner occupied FHA as Benjamin mentioned above.