Creative workaround for granting edit rights to individual jobs for a group?
In the past to solve this I've created a web based app to allow users to change jobs.  The app connected via a sysadmin login, but only allowed the user to edit/start/stop the jobs that they had access to via the app.

Another option would be to go the single login route, but have auditing enabled for that login specifically and make sure that the auditing tracks the computer name as well as the login. That way if someone does something stupid you've got an audit trail and it'll tie back to their computer.

Group's can't be used to own jobs as the job runs under the context of the job owner.

There does need to be a better security model for jobs however.