Guild Wars 2

Let’s say I had World Completion before HoT was released, and got my two gifts of exploration. Will the four new zones make it so that I’ll have to get World Completion again? And if I do, will I get another two gifts of exploration?

No. HoT maps function separately from world completion – just like Silverwastes, Dry Top, and Southsun.

Completion of each HoT map gives a unique gift, combining the four gives you a Gift of Maguuma Exploration or something.

But it’s currently bugged so that if you have world completion you can’t get the new maps’ map completion rewards. Still bugged, last I heard. And I know for sure the rewards weren’t given retroactively – yet.

No. The sets of maps are not related. There are different rewards for completing HoT maps (once the bug is fixed).