Though I think it's an even more general mechanism of association. And places might also be easy to remember because they also contain many elements we can associate. You can call it the connectedness of a memory. You can also try to repeatedly explain to others something you want to remember or whatever.
Could be, but to me it seems our brains are optimized a lot for operating in the spatio(temporal) world, and so spatial connections in particular seem to fit the wiring of our brains particularly well.
You're probably on to something there. Hundreds of millions of years of evolution for finding food and avoiding predators. At best: a few thousand for managing linguistic skills. (or possibly hundreds of thousands, when it comes to our ancestor's pre-linguistic abilities).
