This thread had some good questions and answers. A notable quote from Wraithstrike sums up my thoughts:
An intelligence of - means you can not formulate tactics or adjust to a situation.
If you are prone you will stand up not even noticing the potential AoO.
You will not take the safe route to avoid an AoO.
Flanking will not be done on purpose.
You care basically a computer. You do what you are programmed to do. At best you can act on instincts such as an knowing you want to kill living things.
I think the attack of opportunity is going to happen since it represents you letting your guard down making you easier to hit. Combat is simulated and even if you roll the dice once it is assumed that attacks are always being made.
PS:I am not providing RAW because mindless is not in the rules. This is one of those common sense things.
As far as turning a door knob I would have to say no. Insects are also mindless, and I don't see them turning door knobs even if they have hands.
Insect, undead, and constructs should pretty much have the same problem solving abilities, IMHO.
In your case, you can probably put them in a room with little issue, provided the door is strong enough they can't break it down and/or the area is safe enough that no one is provoking your dead to come out.
As noted in the quoted post, there aren't rules dictating this other than the basic description of Mindless and an extrapolation of how other creatures act. I'll note that he missed Oozes, which are typically Int -.