The radios auto-sync IF YOU HAVE A TEAM LEADER IN YOUR GROUP. If you dont then the freqs will be out of sync. Trust me when i say this, a LOT of time was spent trying to make it work 100% of the time, team leader or not, but we havnt been able to do it. It annoys me as well, but in fairness, it only takes all of 20-30 secs to change a freq on the radios
As for the prefix, i do see your point and it has been noted for the future (and i was thinking about the same thing last week anyway!)