Beds as we know it would be VERY uncomfortable, unless they all slept with their belly down... and didn't move at night, and I think hammocks would have the same problem.
Why would beds be a problem? If their anatomy is at all sane (read: monkey-like), their tail will be able to hang down in line with their spine. Sleeping on their tail will be no worse than sleeping on your back is for us normal humans because of sleeping with our spines against the bed.
From experience, I suspect hammocks will be even better. Have you ever slept in a hammock? You'd think a stretched piece of cloth would be uncomfortable, but they are actually remarkably body-conforming. (They may prefer tightly woven hammocks over more open netting, though, so body parts can't accidentally become entangled. Note that this includes "solid" cloth, which technically is still a woven mesh.)
Couches: I can't imagine one with a big hole on the back...
You suffer from a severe lack of imagination, then 😉. Just imagine a park bench with padding. Note that the seat won't be as deep, or will have cutouts such that you have to sit in a certain spot. You should also read through How would a race of humanoids with tails design [vehicle] seats? which has some alternate suggestions.
Doors: The doors we have would cause an serious amount of pain if closed on their tails, and since they're about 1, 5 - 2m long, I think a "normal door" would be very banned from their society.
Prahara already mentioned this, but I don't see why doors would be a problem. I open a door, I walk through it. It doesn't close on me.
Are you thinking specifically of self-closing doors? Those might be banned, but they also serve an important function. I think it's more likely that, as Prahara noted, your people are just expected to get used to them.
A "doggy door" thing is the best idea I had so far, but... How would they lock it?
...what's the problem here? All you've done is taken a "regular" door and turned it on its side. Why would locking be any different? As a "bonus", you have to add parts to make them not self-closing, rather than the other way around, and the hinges might be easier to build (since they don't have to carry uneven loads).
The potential problem I see with this style of door is that they almost have to use their tail to open it, because the natural leverage point is going to be near floor-level. Maybe that's an issue, maybe not.
They're also going to be rather heavy. (A sideways door can be made so that all the weight is carried by the hinges, so that you only need to overcome inertia. This can work with truly massive doors, like The Black Gate of Mordor. With a door that swings up, you either have to lift the door yourself or design additional mechanisms to offset the weight (e.g. the springs attached to garage doors).
Alternatively, you can make them taller and add a counterweight on top.
Clothes: They can't be dresses or skirts, since, even if they have an extra sleeve for the tail, some taboo parts of the body would show if they lifted their tail too high, or used it to have a good grip on a tree branch.
Why not? If the base of the tail is sleeved, it will be difficult to see what's under the tail, especially if the sleeve is snug. Another option is to have a cord that is tied around the base of the tail to keep the clothing snug against it, sort of like a crupper.