I'm dealing strictly with the sellers themselves. 

I read the permitting process and it seems somewhat strict.

Another huge thing to consider is laws and regulations, many times new investors will jump at Hudson county thinking the proximity to NYC is great for renting (which it is) but many of the municipalities in Hudson county have very strict landlord laws. 

While I don't believe that you need a full blown business plan, strict operational budget, timeline, scrum board, etc...

Quote from @Reed Rickenbach: John - as long as you are still following strict screening criteria I agree for single family.

And the laws and regulations here are very different, not very strict like the states.Prices are high and rents are low over here.

I know in my area they can require it, and we are nowhere near as strict as NY. 

This vary heavily town to town. 20% down is great if buying strictly as investment but if you have a way of owner occupying I would explore that route and apply the 20% down to increasing value of property and instead using low money down loan. 

Since you’re considering converting the upper unit into a short-term rental, you may also want to implement strict rules around smoking or strong odors in your house rules to avoid future issues.

Yea this is a long-term personal play more than a strict STR deal.