B) If my understanding is correct, multimeter is reading 'hold' current. Are latching relay cost effective and easily available ? Are they a drop in replacement, or I need to modify my design (s/w and h/w) ?
the 'hold' current is not something a relay pulls, the relay will pull at V/R the 'hold' current is a requirement for the necessary current to 'hold' the relay.

a simple "kick and hold" circuit:

V+--- resistor ---*---coil--- transistor --- gnd
                  |
                __|__
                _____
                  |
                 gnd

Erik

Dictionary entry: 'relay' : recycling old girlfriends :)