I closed on a nice 4 unit 40k under ARV (and the owner replaced all the furnaces) in November, I listed and sold another 4 unit to someone I had been calling for 2 years, and am in contract on another 4 unit.

So there's probably a decent reason to invest there.It’s a nice place to both call home and invest in ;) 

LOL.. those are legal docs that need to be done correctly and some of those guys have nice groups all put together with a cadre of investors ready to rock and roll.

If we sell our primary house, is it better to pay off the student debt or put a nice downpayment on the next house?

Luckily your closing statement nicely summarizes that number for you. 

Save really nice repairs for the day you decide to sell the property.

Nice to hear your excited to deploy buy and hold strategy in RE. 

One noise complaint from a neighbor and you can lose the income.I feel the same about air bnb, make sure you are ok with the rental by itself as a long term rental, in case any income you get from an adu or air bnb goes away with a city ordinance.Sounds like a marginal deal without, and a nice kicker for upside if you include it.We would probably do the deal if it was currently allowed by the city, especially if it was in a growing area metro area

@Dmitriy Fomichenko nice, detailed response!

I ultimately went with Arizona because I thought I would rather visit AZ twice a year than Oklahoma, Ohio, or Illinois.Phoenix and Tucson were equally good choices- but there were a few other cities I also really liked.I looked for any city/community with consistent job, population, and wage growth.