there’s technically no minimum channel size- it’s just pointless to open small channels cause you get fucked by fees on mainnet when you open/close the channel.

lightning bitcoin is bitcoin in a multisig wallet, shared effectively trustlessly w a single counterparty (can be anyone). the funds between you are accounted for with commitment transactions so you can’t cheat each other.

you could get fucked if you’re computer/node goes down and your counterparty posts an old state to mainnet before you can post the most recent commitment transaction (you usually get 24hrs to a week to contest)