Bismillahi Al-Rahmani Al-Rahim

Tahraha: Khuff

Q 1
What if one takes a trip, whereas the purpose is to disobey Allah. Is
one still permitted (according to the Hanbalis) to wipe over footgear for 72
hours and shorten prayers and the like? Also, what does one do after the end
of this period if he still has wudhu', but needs to pray? What about for
someone who doesn't have wudhu'?

In general, disobedience bars one from taking dispensations. When someone takes a journey for the sake of disobedience (such as going to Las Vegas to gamble) or the very act of journeying is disobedience (such as a child going against his parents without legal justification) then the dispensations typically associated with journeying do not apply. So when the journey is disobedience or for the sake of disobedience, the person can not shorten or join prayers, and they cannot wipe over footgear for more than 24 hours.

If someone wiped on footgear and they had purification up until the end of the 24- or 72- hour period they would need to remove the footgear and remake wudu. It is not sufficient to simply remove the footgear and wash just the feet since consecutiveness is obligatory and not a sunna.

And Allah knows best.

What if someone remembers that he wiped a khuff yesterday (for example),
but is not sure whether he wiped it before Dhuhr, or 'Asr..etc. What does he
Basically: there is deadlock when there is doubt that the time has not elapsed.

As long as the person is certain that the time has not yet expired, then he may continue to wipe and pray using it. If there is doubt  he does not wipe until it the matter become clear--but if he does wipe and it becomes clear that the time had not elapsed the wiping is valid. Additionally, he does not pray until the matter becomes clear, and if he does he must repeat it. (See Ghayat Al-Muntaha 1:35)

So given the above example: before Zuhr the person wipes. But after Zuhr he should not wipe, but if he does and he finds out that the time had not elapsed he may pray. And if he prays before the matter becomes clear, he must repeat the prayer.

And Allah knows best.

Is the list of conditions set for the validity of wiping over a sock
(i.e. wudhu' before putting them on, etc.) an exhausted list, or are there
more conditions you forgot to add? Also, does one have to repeat wudhu' if
he takes them off?

There are a few conditions that I chose not to add because they were understood from what was given or because they were rare. Books like Al-Iqna`, Muntaha Al-Iradat and Ghayat Al-Muntaha include some incredibly rare and bizarre things. But I do not see anything that I forgot to add.

And Allah knows best.

wa al-salamu `alaykum