SUPPORT: One of the best things for me when I play support is if the Hotel in Karkand is held by one side (either USMC or MEC) and the Square is held by the other side. For some reason, even though those flags are RELATIVELY not that important to the MEC (Gatehouse on the 32 man server and the Warehouse on the 64 man server are the key areas), people love to fight a lot for them. You can score lots of support points here by laying down good suppressive fire as your team advances. Get into the prone position. Fire in short bursts (count in your head 1-2-3-4-5, and that is usually long enough). Get up and move - if you stay prone too long, you die fast, because the only thing exposed is your head, and a headshot makes you DEAD. Move to covered areas where you can blend in. Drop ammo bags. Once your team is in the area of a flag, move up and resupply them, or help clean out an area - the LMGs are as devastating as a shotty in CQC.
Sharqi is another good map for support. As you and your squadmates move around the flags that are surrounded by alleyways and stuff, you are bound to accidently run into a couple of "baddies." The LMG will work 'em at close range, unless they are awesome with a shotty or a LMG.
MEDIC: When I'm in a slump (where I keep getting pwn'd, or I'm just slow for some reason) and there's no armor around to whore in (j/k) I like to play commander. If I don't get to be commander, I'll play medic. There's just too many ways for you to be helpful AND earn points. The G36E is a really cool unlock for the "combat medic." Get in a squad that methodically moves and tries to capture flags. Try not to be the first guy to charge into battle - that's what the assault guys are for, and sometimes the support guys. Stay a little bit behind and use the medium range bursting accuracy of the G36E to pick off bad guys when they reveal themselves while trying to shoot at your squad members. After you take the baddies out, revive any of your buddies, or start dropping med packs. Of course, you can medic whore at Karkand Hotel, but that gets a little boring after a while.
With the shock paddles, keep in mind that with the new patch, DICE did something so that if you toss all three of your medic packs out, it takes a while to get your shock paddles to recharge. If you toss two of them out, you have one charge left on your paddles, and then they need to charge. So, I THINK you only have a max of 3 charges to give out - provided you have recharged fully after tossing your last medic pack. With that in mind, don't just chuck 3 bags out mindlessly. You never know when you might need that one charge that can quickly revive a teammate to help you hold a flag or cap a flag. That philosophy helped me a lot playing Warlord last week - we'd try to cap Insurgent's Hideout, and one of my mates would get killed. I'd be able to revive either one of them because I made a habit of not mindlessly tossing out my medic bags once we got to the flag.