Maybe someone else has more experience in analyzing that type of situation.

It is a hard to answer question without know more about the specifics of each deal and your personal financial situation, goals and risk tolerance. 

I’m in a similar situation, I have one triplex.

In these situations, how are the note payments accounted for?

proper notice to enter is usually defined by the state as 24 hours notice. some states require 48. that is your starting point. that being said, coming through with a high amount of showings can be considered as disrupting the tenants right to peaceful enjoyment of their home. if you plan on coming through with one or two, you should be ok (legally) to give tenant prior written notice and come in regardless of their objections. if you think it may take multiple showings, you are likely better off to work with the tenant to set up a block of time for an open house. in extreme situations, you can consider offering a gift card to a local restaurant or movie theater to get them out. the tricky part is striking a balance between what is legal, entering with proper notice, and what is fair and reasonable, since the tenant can purposely leave the house an extreme mess to make it harder to re-rent, badmouth you to potential renters, and may even try to refuse entry. how you approach will depend on your relationship with tenant.

The current owner is about 97 and cannot remember what the situation was. 

Is there a better option people would suggest given the situation at a high level?

You'll just need to find the balance of giving amazing and caring customer service to those sellers in need along with remembering as an investor, you are a business and you will need to create a win win situation for both you and the seller.

Everyone's situation is different so it really depends on an individuals situation.RE depreciation: Under recent tax changes ALMOST everything is deductible in the year its paid.

.- 3-4 units still puts you in the residential category- 5 or more units is commercial residential and most lenders will expect you to have experience and will generally have more restrictions on the lending process- A 10+ cap rate in the Boston area will be extremely challenging to find unless you are planning on a massive value add or redevelopment- No idea what your personal financial situation, but a 3 family in Worcester versus a 20 unit requires a very different upfront financial commitment.