Here's the deal with bell-ringers - because of the relative stability of the society and government (up till now) there has been little need for law enforcement. A single trained champion could drive away most small bandit gangs or stop inter-council fights or placate mean drunks. When the challenge was too great for a bell-ringer to handle on his own, she rang the bell. This didn't happen very often, except when large-scale bandit raids happened or a monstrosity of some sort wandered out of the Plague Lands. The ringing would warn villagers to gather to the town center (This is starting to sound like Age of Empires 2) and would be projected by the bell's engraved name-magic to the state capital, summoning the militia. The city-states are not too large, so dog sleds could bring the militia to most villages in a matter of hours. The bell is immense and non-portable, so most bell-ringers would be bound to a single location. Up to this point, most bell-ringers have acted as bodyguards to village Magistrates or crossing-guard-type peace-keepers. The system is in trouble, though, as a threat has appeared (the Plague Priests) wielding sick magics that could level any village in minutes if they managed to defeat the bell-ringer.
There could be exceptions to the stationary village champion idea, of course: the mobile bell-ringer in training, the bell-ringer replaced by a council toadie and cast out, the bell-ringer whose village has fallen to the Plague Cults... A moving bell-ringer with a portable bell sounds like a cool idea that could be fleshed out. Run with it if you feel like it.
As for needing to read the rulebook beforehand, I think that this playtest would actually work better without everyone spending a lot of time with the rules. The idea is to have a character concept in mind and then challenge the rules on the spot to cater to this concept. If players spend a lot of time with the char-gen system, they learn to min-max it (and BESM is kind of susceptible to this) and they modify their concepts to make room for the coolest "powers" they find in the rules. The rules are very simple and stripped-down, so I think we can tackle it without a lot of review of rules.