Hey,
so first of all let me ask a fairly basic question. Why not UMG? It’s super easy to setup and you just get events for each button, can set design, behavior and all that in an easy editor. I would recommend it.
However there may very well be a reason I don’t know which requires you to do it like this so let me try to help you here.
“Switch on Name” allows you in the details to set the possible name strings which will be chosen as they come up. This should already help you with the selection issue.
To address the cameras I’d suggest to just use again those names and a function in your player controller or character. I’m not entirely sure anymore which functions are available in HUD but there should be something like “Owning player controller” or similar. Like that you have an easy connection to that and can then go on to find your camera manager or some function in another part.