Questions about netgame syncing and Lua scripting

So as anyone who's tried to play Space Chase in a netgame would know, I've been having a ton of problems getting that level to stay in sync in a netgame. The following are mostly questions for those developers that deal with the netcode, or Lua, or anyone who knows enough to answer them.

• What does the game do to determine if it needs to resync? I'd like specifics; like, if player positions are checked then what's the margin of error? Basically, how could I brute-force the sync checks in Lua if players are currently all forced into a specific position and angle?
• What all is sent in $$$.sav when a player joins/when the game resyncs? Are custom Lua variables tied to an object included in that, or am I going to need to handle it myself? If the latter is true, how would I go about that?
• How does the NetVars hook work? It confuses me. I know it passes a function that can be called to network certain variables, but is it only called when a player joins, or is it involved in resyncing, or what?

Thanks for your time.

As far as I've heard (source: JTE himself), the NetVars hook may actually be completely broke right now, so eh. =S