I did it!
finished the 1st mission
It was not that bad actually, I had 3 "heavy hitter" light mechs + 1 scout; which meant that as long as I kept the enemy at range; I was able to punch them with an AC10, a PPC and a Large laser. Also, with all my mechs at tactical advantage, it was not that hard to beat the Shadow Hawk as it had to pass the gauntlet of 3 big guns before it even shot back; and of course I kept distance to avoid its powerful melee attack
Not surprisingly, the Spider ended quite beaten, as its job was to dodge attacks and bring the bring the enemy to my kill zones
the commando also ended with some damage, the urban mech came home with only one round left... I have done much worst in previous games with the standard lance