

Hi, network engineer with a specialization in mikrotik, you’re on the right track.
You would configure the router to use one radio as your WAN connection, then NAT your internal connection using a masquerade rule. Pretty simple setup.
Some notable drawbacks for this dependent on model is that you will lose wireless speed as you will be using your wireless for upstream and downstream devices. This can be solved by using an AP on a different channel.
Note that mikrotik gives you a lot of ways to cut off your hands, so use safe mode for everything.
The specific topology you’re wanting to set up is something they teach you on day one at any mikrotik certification course.
Yeah, a 2nd AP wired into the first router would eliminate any performance hit of having the router do both. Hard to say what the impact would be without testing though.