Sorry for yet another newbie Q:

Have FLO rims with 23mm contis on them. I hear the “25mm is so nice...and more aero, and more comfy and...”

My questions:
how do you know if 25mm tires will fit on your rim (trial and error, or it’s pretty standard they will)? I know spacing to frame is usually where issues of fit come up(or so I’ve read), but tire to 25mm rim should be fine?

Does 25mm tire need 25mm tube, or does a 23mm tube work fine?

Is there anything I should know? Just wondering if I should move to 25mm after I’m done with these 23s, and what I’d need if I do.

Thanks.