Changing the text state of a repeater onClick

This is a multi-part question really.
Question 1: I have a bunch of repeaters [buttons specifically] linked to a dataset that filter a gallery. What I can’t get it to do is get the text to go bold when one is clicked, and return to normal state when another is clicked. I’ve searched a few different forum posts about similar issues, but the solutions don’t seem to work. This one is probably something very simple that I’m just messing up.
Question 2: Is there a way to carry these repeaters onto a dynamic page [which opens when an image on the gallery is clicked] that not only maintains the filter, but stays bold AND sends you back to the main gallery when clicked?