I don't understand exactly what you mean for the first option, but second one would be nice to have
I would like to reinforce my militia just like militia can reinforce my mercs.

Should be enough to know exactly what sector enemy plans to attack (direction of enemy squad movement) using radio operator or snitch or scout trait, because movement between city sectors is much faster than outside.
Another good idea for defence is to manually set militia positions, so they will remember them between battles and appear there when recreated.

"No" to 1 and "No" to 2 from my side. Players are supposed to plan their defenses instead of using some cheat mode.

Showing enemy movement directions, like Seven suggests, could be an option as part of the scout trait. I would restrict it to a "scouting" assignment however. Can't scout while sleeping, repairing stuff or hanging out at the bar.

A scenario: I put 6 soldiers on different duties, repair train etc.
I see enemy near Sector E13 I move my 6 soldiers to E13, put them in position, reasign all roles turn the clock forwards. The enemy moves next to C13, again I move to C13 reasign, position, turn the clock forwards....

Isn't A.C.A facility assignment providing this info already?