Network for Apartment building?

Hoping for some advice for managing a network for a multi unit apartment building

I want to share a network for 2-3 units with a single gigabit connection.

Ideally I want to use an OpenWRT router such as a NanoPi R6S, or a R4S, or something similar. I want to use SQM piece of cake to shape the connection.

I'll then buy a Belkin RT3200 or something similar for each unit, and it'll be hard wired wired to my NanoPi, switch, or whatever I want to use.

Will each router be able to have their own WiFi password to get on the network or will they have to be shared?

What would be the easiest way to remote into my router if I'm not physically at one of these apartments?

General thoughts and suggestions appreciated!

yes, and inaccessible from the other networks, if you set it up correctly.

VPN ? SSH ?
depends on the use case.

I'm not too savvy when it comes to more advanced network things, but it sounds like I can VPN into my NanoPi device then while it's also shaping my traffic?

Perfect.

Sure, those are different things, unrelated to each other.

I think he meant are the devices powerful enough and/or the firmware flexible enough to support routing with SQM shaping while also handling a remote VPN connection. The answer is a qualified yes. SQM does require some horsepower, but just remoting in over a VPN to do admin shouldn't tax the system much.