If you leave an event going it will remain going until you trigger a new event. At that time the old one will vanish as there can only be one event going at a time.

Not sure if that includes the wolf hunt as that event happens in the mountains or plains away from a base.

The main thing to do is go slow. Do not rush to kill the boss as that will just make the world harder.

For example I don't kill the first boss until I have scouted out copper deposits and have some cores. You need the cores to smelt the metal so it is pointless to get the pickax before that.

For the second boss I won't kill him until I have scouted out a swamp and have swamp food and have iron crypts marked on the map and portals near by ready with a base set up to process or transport from in a near safe zone. Again there is no point in having the crypt key if you don't know where any crypts are.

This will let you work on your skills as well as upgrade your equipment and food to be ready for each biome in relative safety and ease.

Using trenches and workbenches to prevent spawns in your base is just basic home defense.

That said though if you gear up properly you can face them well enough. With good defenses you can just crouch and wait it out the clean up the leftovers.