I would argue, that the easiest way to kill a mimic is to wear a piece of the moon butterfly set and stand near it, as the armor can kill a mimic with poison, without the mimic being able to attack. This is also an easy way to check chests for mimics, as it deals no damage to normal chests.

This page says that mimics respawn- this is false. A mimic will not respawn unless the area is cycled to a higher level of NG- either through a bonfire ascetic or through actually going into NG+ (and beyond).

Isn’t there one in majula in ng+

Note: They will grab you and do incredibly high amounts of damage as they reveal themselves after being hit, if you are standing close to them at all. It is best to smack them, let them assume their true form by backing off, then wallop it afterward.

Attacking the closed chest from behind will not save you from being munched on.

In Doors of Pharros, I was on the stairs and the mimic was not and somehow the mimic teleported me into their mouth and vored me

If you do enough damage, you can kill them before they even have a chance to attack you and move since their "startup" animation is fairly lengthy and they don't have any iframes while they're doing it.