Thank you for getting the whole project rolling!
Here are a few thoughts on the subject from my side:
I think that the Firefox release cycle is one of the most practical time units or periods to adopt in this case. Mozillians usually rally and interact the most for the purpose of releases and many activities that invite contribution across Mozilla fall into that rhythm.
Therefore, voting (done online) for community coordinators could be done one week after each release, to reflect and represent ongoing engagement into Mozilla’s mission.
(That said, some parts of Mozilla’s mission may have different suitable time periods to consider. For example, MozFest happens once a year, not every 6 weeks - and has a different “life cycle”).
Each member of a community could have 2 votes to give to other members of the same community. (A community in this context would probably be a group of people gathered around a geographical location, a locale or a project with a significant pool of distributed contributors, e.g. MozFest)
Voting could be done via mozillians.org (an account would be required for voting and being a candidate). One can’t vote for themselves, only for others. Voting would be public (the number of votes would be clickable and would show who voted for a person). Every vouched for Mozillian would be eligible to receive votes.
Another interesting alternative could be giving a persistent “thumbs up” that could be removed, if the opinion of a community member about the person they gave the “thumbs up” changes. There would be no “thumbs down”, only a “thumbs up” option.
In general, feedback could be ongoing (and online) and grouped by Firefox release (every release or every two releases, whatever’s more convenient). All feedback could be transparent and accessible to everyone within a community. We’d probably need some courses on providing/receiving constructive feedback for everyone (myself included), but that investment could go a long way towards a more honest and open community.
Feedback options could include a numerical scale through which feedback providers could express their understanding of a person’s contributions and performance in making Mozilla’s mission happen. The scale could measure several aspects, like “being on time”, “clarity in communications”, etc. (in case you need metrics for these hard to distill qualities).
The leaders could be the 3-4 people from each community that receive the most support from other members. That number would differ depending on the scale and needs of the community, but ideally would always be larger than 1.