a) Install ok
b) Lock will brick. Edit @cxtinac in the case that the /e/ SPL is 01 June 2025 as found by others [1], [2]. (Otherwise equal SPL would be ok to lock.)
c) carry on unlocked ok
d) Keep checking … July likely omitted … August likely 1st Aug not 5th August.
See also [1] Please put the complete date of the security patch date in the release notes
Perhaps see also Revert back to stock OS and relock bootloader - #4 by aibd
Exactly, the build date is irrelevant to Android SPL.
[2] Fairphone 6 /e/os 3.0.4-a15 security patch not june 5th?