Unable to answer "What diameter is specified on the sign for this fire hydrant?" for osm.org/node/10691386554 via StreetComplete 53.3:

No number on sign.

Attached photo(s):
https://westnordost.de/p/170393.jpg

Unable to answer "What diameter is specified on the sign for this fire hydrant?" for osm.org/node/10694079012 via StreetComplete 53.3:

No number

Attached photo(s):
https://westnordost.de/p/170743.jpg

Has this been demolished yet? And other buildings around it?

Wrapped Brighton

Unable to answer "What can be left here for recycling?" for osm.org/node/9291402081 via StreetComplete 51.1:

This is not public. It's the store's bin area.

how does this path traverse the building?

Ursa Court

This building is The Dance Space
https://southeastdance.org.uk/the-dance-space/
Address details:
The Dance Space
2 Market Square
Circus Street
Brighton
BN2 9AS
https://southeastdance.org.uk/the-dance-space/find-us/

The stretch of the A26 from the Cuilfail Tunnel south to the roundabout is known as the "Southerham Road".

Is "Hanover & Queen's Park" a suburb of Brighton?

can it be a node instead of tagged as a name on the residential way?

osm.org/way/208321345