Good question. I don't know exactly all the technical details (I mean how the code is executed), but I will try to explain it from my own experience running various nodes for years.

Yes. In theory yes, you should have a backup for the channels with all movements, like CLN is doing. LND is doing SCB, static channel backup.

SCB contains information about each of your peers, how to reach them and your channels. With that information, when you trigger the restore procedure, it contact the peers and negotiate the closing fee and the balance.

If your peer nodes do not receive the answer from your node (is dead), then will consider their last commitment as true and initiate with that information the closing. That's why there's a grace period of 144 blocks in which you can reclaim another status (if you have it) and rebroadcast it again. Otherwise will be a cooperative closing, when both peers are online and send the last correct status they have it.

So yes, you are entitled to worry that a peer can initiate a force closing with another balance and steal your funds. Is better to choose wisely your peers, especially for a private node like Zeus, that for the moment do not have an option for watchtowers. It is in the pipeline but not so soon.