If I take control of a opponent's minion, would I have to use that card's house, or would it be usable when I choose the card that took control of it's house. For example, if i destroy a logos creature with Overlord Greking, would I be able to attack with the logos creature when I choose Dis, or would I have to choose Logos. Also, if my deck doesn't have logos, could i choose logos?

Aside from using an ability that lets you use a card off house (e.g. Gauntlet of Command, Dominator Bauble, Experimental Therapy, etc.), the only way to use the creature would be to call that creature's house in Step 2.

This is clarified in the rulebook under Step 2: Choosing a House:

Quote

If a player controls a card that does not belong to one of the three houses on their identity card, they may (if they desire) choose and activate that house during this step instead of one of the three houses in their deck.

Yeah, it is great if they have a house that you normally can call. Otherwise, you are just removing a creature sometimes without it dying so it can't be reshuffled back into their deck or archives.