The “Event Chairs” text, and pretty much all other public side text, can be easily changed, or hidden, using the Customizer extension.
The current data structure is not really setup to allow the kind of repeating signups you are wanting, and single email notifications. I’m stuck with an old data structure from the original plugin from another developer that I forked into the current main/free plugin for our needs for my son’s school PTA website a long time ago. I’ve expanded on it a bit, but it’s not really a good database design.
I’ve been working on a new “Events and Signups” plugin, where I’m starting over from scratch with a much better database structure and better object oriented coding. For that I’ll have true repeating style events, where signups can also repeat (optional), and much better organization overall, plus many features that are now extensions to the old plugin will be built-in (calendar, custom fields, etc.). But, that’s quite a ways off from being ready for release.