Yes, but the router will need to have a smart connect feature for that.

yes.

i don't remember doing anything extra.... set ssid, tick 5ghz.

it will do the rest... say, ssid abcd for 2.4ghz, the other will appear as abcd_5G, use same PW.

yr devices, if dual band, will go for whichever is stronger.

this router for its price is pretty good - stable and reliable.

for my unifi 800mbps:

ethernet is max if yr device is gigiabit - my test 860mbps on one device.

wifi... <40ft, 5ghz strong... 200-400mbps;  >50ft, likely it will switch to 2.4ghz, get 20-30 mbps, still good enough for most purposes.

been using this rtac1300uhp router for 1.5 years now.
remember to update to current firmware:
3.0.0.4.380_8457