Are there really two different fire hydrants at this point? One with reference number 260 and one with 261?
If not, what is the reference number of the fire hydrant here and where is the other one?
If it is true, please comment here and someone please mark it as a note in the two nodes.

Unable to answer "What diameter is specified on the sign for this fire hydrant?" for osm.org/node/8582590415 via StreetComplete 38.2:

No sign, photos of the above ground fire hydrant attached

Attached photo(s):
https://westnordost.de/p/73583.jpg
https://westnordost.de/p/73584.jpg
https://westnordost.de/p/73585.jpg
https://westnordost.de/p/73586.jpg
https://westnordost.de/p/73587.jpg

Unable to answer "Is this barrier (usually) locked?" – Chain – osm.org/node/9388073075 via StreetComplete_ee 61.0:

Seems like only an informational sign so access should be set to yes for pedestrians and similar transport modes, off-road bicycles can also probably pass on the side

Attached photo(s):
https://streetcomplete.app/p/306759.jpg
https://streetcomplete.app/p/306760.jpg

Unable to answer "What surface does this road have?" – Camí de la Llódriga (Track / Land-Access Road) – osm.org/way/248654166 via StreetComplete_ee 61.0:

No option in street complete fitting, is there a better tag for this?

Attached photo(s):
https://streetcomplete.app/p/306756.jpg

No overnight parking, height restrictor at the entrance / exit of car parking. See photos

via StreetComplete 49.0

Attached photo(s):
https://westnordost.de/p/120462.jpg
https://westnordost.de/p/120463.jpg

There are 2 nodes near this without tags, are they supposed to have some and does someone know the meaning or is this a mistake and they should be deleted?

New building West of the current construction

via StreetComplete 55.1

Attached photo(s):
https://westnordost.de/p/189603.jpg