I have had this router in continuous use for about 1 1/2 years. My router is absolutely silent and I have very "sensitive" hearing^^ But it gets very warm like most "high performance routers". The lights are embedded in the housing and level with the rest of the surface and "look" upwards. So they can be covered in one go with black insulating tape, for example. Otherwise, of course, it flickers away. One LED because it is switched on, one LED for the WAN interface, one LED if the antenna is active and one additional LED to signal operation, then of course one LED per LAN port. So with one client and W-Lan active, a total of 5 LEDs are lit. They are not too bright and have a blue light. I would mask them in favour of the router. If you are an aesthete, I think you have lost.
It is by far the best router I have ever had, and I have used many. With an internal scheduler, you can schedule when the antenna is off or on. By the way, the power can also be adjusted, especially in the bedroom many people have concerns about the transmission power.
Completely noiseless. And the tiny blue LEDs only flash occasionally and can be taped off if necessary, as already noted. A very good router, by the way.
It is ASUS RT-AC66U (you called this version “B0”) with USB 2.0 2x, according to data sheet
https://www.asus.com/us/Networking/RTAC66U/
ASUS RT-AC66U B1
It has USB 2.0 1x and USB 3.0 1x, according to data sheet
https://www.asus.com/ch-de/Networking/RT-AC66U-B1/specifications/
Yes, of course, just put it into AP (access point) mode. In this case it switches the DHCP server and routing functionality off, and become a "standard" switch.