You could always drop 1 boy in each squad and a loota to get a
PK for a nob.
As for the big mek he has a burna so he can deal with the stronger groups of enemies, the warboss though is the important on for the
PK as his
str is doubled and using the power of the waaaaagh you can assult 12"

gg for any slower moving vehicle
but i do recoment having one squad just for mobbing up