Unable to answer "How is this power line attached?" – Power Pole – node/4386430077 via StreetComplete 63.1:

Fixed horizontally with one supported from above

Attached photo(s):
https://streetcomplete.app/p/345782.jpg

Unable to answer "Is there a crossing here?" – node/3787849662 via StreetComplete 63.1:

There is no sidewalk directly on the south side.

Attached photo(s):
https://streetcomplete.app/p/345765.jpg

Unable to answer "What’s the surface here?" for way/125393350 via StreetComplete 47.1:

It's that green rubber-like surface used for basketball courts. Not sure what it's called.