If your Mikrotik device can act as a RADIUS server for external devices using 802.1x, probably. You may need to dig up instructions on how to do that for your particular equipment, but Mikrotik's wiki is pretty great and there's a decent community for them.
Yup, easy as pie. We have our APs either use local Meraki DHCP or external DHCP, then radius is handled by separate external servers. The only real core requirement is for the tunnel to be up to hit the external servers.
If your Mikrotik device can act as a RADIUS server for external devices using 802.1x, probably. You may need to dig up instructions on how to do that for your particular equipment, but Mikrotik's wiki is pretty great and there's a decent community for them.