If you keep there /22 and /24 as an option, than there would be no problem.
No please, don't let LIR choose. This will only complicate management of
resources.
It's a simple flag, "/24 sufficienct: yes/no".
In a FIFO, a LIR asking for /22 would delay a LIR who only
needs a /24.
Yes, that would be the case. Since that second LIR won't
have the slightest
idea when it would receive IPv4 anyway, I fail to seen an issue
with that.
On the contrary, it emphasis the fact that IPv4 is over.