The LEM had ...
... four oxygen supplies : two, in the descent stage, provide oxygen
during the descent and lunar- stay phases of the mission: two, in the
ascent stage, during the ascent and rendezvous phases of the mission.
The caution and warning limit values can tell us the range of pressures expected to be nominal.
An absolute pressure transducer in each descent oxygen tank feed line
generates an output proportional to tank pressure. The output is
routed to the Instrumentation Subsystem (IS) ,where it is
conditioned to provide a telemetry signal, a caution indication, and
through the 02 /H20 QTY MON selector switch (panel 2) , a
display on the 02 QUANTITY indicator. When descent tank 1 pressure
drops 1 below 135 psia (approximately 5% of capacity), a signal is
routed to the O2 QTY caution light.
This tells us the nominal pressure in the descent tanks was between 2700 and 135 psi (~187 to ~9 bar). Page 2.6-13 confirms the upper limit "Descent tank pressure, approximatey 2690 psia..."
A pressure transducer in the fill line of each ascent oxygen tank
generates an output that is also conditioned in the IS to provide a
telemetry signal, a caution indication, and a display on the 02
QUANTITY indicator. The quantity of oxygen remaining in the tanks is
read on the indicator by setting the selector switch to ASC 1 or ASC
2, as applicable. The 02 QTY caution light goes on if, before
staging, the pressure in either ascent oxygen tank is less than 684
psia (less-than-full condition ). After staging, the signal that
causes this indication is inhibited; instead, the light goes on when
pressure in ascent tank No. 1 is less than 100 psia.
This tells us the nominal pressure in the ascent tanks was between 684 and 100 psi (~47 to ~7 bar)
From LM Handbook Volume 1 page 2.6-7
Speculation about why liquid / cryogenic O2 wasn't used: Desire to reduce weight and complexity of the LEM.
Have not found temperature data yet.