About unarmored infantry with kill values, I think there may be something in the full rules that might give a unit an armor save if in certain types of cover.
In the original SST rules there was obscurement (+1 to armor saves), hard cover (+2 armor), and fortification (+3 armor). There was no change to target and kill scores. In BFE, cover gives you +2 to target and kill scores, but no armor benefits, but I suspect that there may be some in the full rules in the future. I know I'd love to have a cover save of even 6+ for my PLA since they die really easily. But man, it'll be hard to dislodge USMC or EFTF troops from cover if so.
And yeah, that Fedayeen squad is nasty, especially if you screen them with some cheap an plentiful MEA basic infantry.
The Hillux transport trucks are pretty costly because they're faster, have a weapon that can fire multiple turns and on reactions, can carry more, and their troops can fire out the back. Whereas the Shadow is slower, but better armored, and has an AT missile. The shadow also can't load up a full USMC squad (6 passengers), they have to have at least two to transport a full squad. Whereas the MEA technical can transport up to 8 passengers, that's a normal MEA squad. Then if you want to give the technical some AT ability, just load a squad with some RPGs on it and zip around the battlefield firing RPGs at the tank's sides and rear.
You'll usually see a USMC player fielding at least two shadows rather than just one, unless they're using it to ferry around a small special forces squad.