You're all correct except maybe the part about passing out post-game cold ones
The NHL has subtle differences but in USA Hockey it's largely the same. As a linesman I call offside violations and faceoffs, and conduct every faceoff except center ice faceoffs (in USA Hockey you can only have those to start a period, after a goal, or for premature goalie substitution). There are actually 13 specific reasons for which a linesman can stop play. I don't recall all 13 of them exactly but when I'm on the ice as a linesman I'll just instinctively remember if I can or not. Other misc. reasons why a linesman can blow the whistle are: net off pegs, puck out of play, puck played with a high stick, hand pass, injured player, too many players on the ice, puck entering the net unobserved by the referee, spectator interference, safety hazards like broken glass panes/open doors, players equipment issues/violations*, etc.
Also what's little known is that a linesman can report to the referee, at the next stoppage, any infraction which he believes would warrant a major, misconduct, game misconduct, or match penalty (though it's the referee's final decision whether or not to assess the penalty). I've done this once in a Bantam game, we were using a 3-man crew and I watched a player in a scrum down low cross check an opponent hard in the back of the neck. I told the referee about it and he kicked the player out of the game.
*Youth play: if a player or goalie's helmet comes off, play is stopped immediately, period. If a goalie's glove or blocker comes off, play is stopped immediately unless there's an "imminent scoring chance".
*Adult play: if a player's helmet comes off, he has to either pick it up and put it back on or skate to the bench to be substituted. He can't participate in the play without a helmet on. If a goalie's helmet comes off, play is stopped immediately. The rule about the goalie's glove/blocker is the same as youth play.
Edit: and yes, while not codified by the rules of play, a large part of a linesman's duties is to separate players involved in altercations. There's actually a method to it that they teach. Referees aren't supposed to get involved unless it's dangerous (such as one guy being pinned down on the ice and the other guy punching him repeatedly in the face). It's why I find it amusing again when there's a line brawl and people get mad at referees for not helping break things up. They're specifically trained NOT to...