Heimdall is the Guardian of Asgard, and the keeper of the Bifrost.

[As for Ragnarok, he has no idea what that is. The movies haven't mentioned it and the comics say it's a cyclical thing where no one remembers wtf happened and he had no idea until Odin's giant sentient severed eyeball told him so, so either way it's an unknown to him.]

As for the matter of Ragnarok, you have the advantage in that I have not read the tales of which you are speaking, nor have I experienced them.