Concerning 3. (shelter vs rescue-organizations):
The one thing that's problematic is that shelter doesn't have a tag description, but the word has different meanings:
- protection against the environment and weatherweather;
- refuge, asylumasylum;
- a place to live that's not your ownown;
- a place where you can adopt pets.
The meaning and interchanging use may be caused by the different ways shelters work globally. There are countries where shelters euthanize animals after a very short time for a lot of reasons (including lack of space and adoptability of the animal) and there are countries where shelters are forbidden to euthanize for any reason but to prevent suffering. There are countries where rescue organizations offer common pets for adoption and other countries where they pick up injured wildlife (or feral stray cats) and release them back into the wild after nursing them back to health.
Depending on where you live, each tag may mean a different thing. In my country, any place where you can adopt a pet would be called a "shelter", regardless of whether it's run by a rescue organization or not.
I recently learned that shelters can have very different names in different countries, like "animal/community health center" or "animal sanctuary". If people translate those local names into English, the most probable outcome is "shelter", even though the type of organization might be considered a "rescue organization" in other countries.
My proposal is to define shelter as a synonym to rescue-organizations and to add a proper description to housing (which has 0 questions) to make it mean "shelter from the weather".