The best thing to do is to talk to every local and regional lender in the area to find out what their appetite and requirements.

I plan to replace the basement ceiling with 5/8 rock (it's a popcorn mess now) for part of the fire suppression requirements,  but would probably run into additional issues with a separate unit, even as an STR.Good idea.

More properties is more risk/effort, so I think ultimately you have to determine your appetite for both of those.

I can figure most things out but I'm no master carpenter and my appetite for doing big projects myself is non-existent.

It is all about your risk appetite and the deal but usually a 5 year hold is 15% IRR plus.4.

I may consider house hacking a SFH if I lose my appetite for the new build of a duplex.

Hadto several permits to update electrical , plumbing and install newfire suppression between the upstairs and man unit .

I would make sure you are familiar with competitive buildings to yours and that will help you figure out asking rental rate for your building and whether tenants are used to paying services as NNN, full service, or some type of modified gross since this factors into overall rent and what prospective tenants' appetites are in your market.

Committees of local bankers make decisions on what they have an appetite for.  

I also have a pretty good handle on what their appetites are.