Mostly agree, M4 is one of the easiest weapons to use, I like it more than the laser-accurate ACR. I'll agree with your setup as well with one acception.
If he's having issues killing then Commando isn't going to help as much as some other perks. I rarely remember to knife a guy, I'll just shoot him to death. I think that Steady Aim or Ninja will help him the most, Ninja gets my vote because A) you're instantly off all the heartbeat sensors (granted, not many people use 'em) and B after 50 close range kills you have silent footsteps, this is invaluable for being...well...stealthy...or even just tactical. I can't count the number of people I've killed simply because I heard them coming.
Also, if you're lvl 32 in the near future you'll unlock Claymore, it's cheesy but very helpful for getting some easy kills. Just set it up facing a doorway and wait for the +100 to pop up (assuming it's a high traffic area). I actually played a game of TDM the other day where the enemies kept charging that center coffee house on Invasion and I kept setting up claymores, I got my first 9 kills without firing a bullet! That includes two double kills with claymores.
Finally, if you get killed by alot of aircraft don't worry about having a combat 2nd weapon, get a Stinger missile (you've unlocked it already) and take care of the aircraft. Good points and you'll live longer!