Don’t use duct tape, if you rent, the adhesive hardens and will get left behind. Using like packing tape or maybe something professionals use would be better. If the door is metal, they make magnetic curtain rods, we use them on our doors but there will be a limit to the weight of the curtain it can support. Paint on the windows may work, and scraping it off later should work, but is a pain and can scratch the glass.

I find sitting is worse with the problem. Pressing on the taint area helps to get the rest out.

Yes, though religion is more problematic due to their holy books having loads of these things they can and often use to justify it. Shit people will always exist, but let’s not pretend the situations are similar.