It looks like your seller wants to seller finance the deal to 'be the bank' - which can be great - maybe you can negotiate a better deal on interest rates than what is currently going on in the regular market - which would be awesome.As for which home first - I would definitely go for the duplex you are already in.  

Do our regular rent increase and then add on an extra $100 or $200 because you have to chase the rent Let the tenant know now that their rent will increase significantly if you have to chase them for the rent every month. 

This is especially true the finer the market is.I see a lot of different strategies from serial investors I work with regularly, and would be happy to learn more about your finer details as such.

Attend local meetups regularly.

Backstory:We rent the ADU out regularly via STR or MTR and live in the main house currently and are looking to size up.

Again, the BiggerPockets store has some books for this or you can learn by watching podcasts, reading blogs, and interacting on the forum.

Again, the BiggerPockets store has some books for this or you can learn by watching podcasts, reading blogs, and interacting on the forum.

Houston isn't making 4 unit buildings regularly.

Also, Z Wave and Zigbee radios are in sleep mode 99% of the time whereas WiFi radios are communicating pretty regularly.

They are not as scary as some make them out to be, you just want to be certain that you can regularly contribute to the principal of the HELOC/home equity loan (on top of your monthly interest only payments), so you can pay the balance off within a reasonable amount of time.