I haven't played in like 2 weeks, because I had to ship my Xbox in to be repaired, but I'd like to chime in on a few of these topics.
I got several Nukes and I stopped because I went to Hardcore which is my preferred game type, but I find the best class set up is:
SCAR w/ Red Dot/Holo
M93 w/ Red Dot/Holo
Claymore
Scavenger Pro
Hardline Pro
Steady Aim Pro
Kill Streaks: Harrier, Chopper Gunner/AC-130, Nuke
Usually before I switch to Nuke mode I check the room, if people are running Stingers and Javelins, you might have to find a new game, the people that use those weapons have a vendetta against air support and will shoot them down right away. You can opt for the AC-130 as it works a tad better against those weapons but it makes it harder obviously since you have to be pretty good to chain the AC-130 to the Nuke. Once I feel I can get a Nuke I go into slow and methodical mode, set Claymores behind you so your back is protected and when you get kills set another Claymore (remember you can only have 2 out). Just slowly go around and pick people off, you don't have to camp but it helps, once you get the Harrier look where the other team seems to be spawning, though often times it seems best to put it near a flag they own, if they don't shoot it down you got your Chopper Gunner, hide somewhere and possibly protect yourself with a Claymore. From there it is just getting the rest of the kills and if no one uses Stinger or Javelin you are on the road to the Nuke. Sometimes you will be close to the Nuke but the Chopper gets shot down or just ends, go back to slow and steady and finish it off. Though at this point you will be like 21-0 and people will begin to hunt for you so be extremely wary, everyone knows the Nuke is coming and the other team wants to stop it at any cost. This is just my most common Nuke set up, but I've gotten Nukes sniping on Derail, sniping on Underpass, rushing around on Favela, etc. I've also had quite a few close calls where I was 22-0, 23-0, etc and the team goes nuts after me or I just fuck up and miss a kill that I should've had.
On Hardcore the weapon differences rarely make a difference, but in regular I have noticed a few weapons do stand above the rest. The SCAR is in my opinion the best gun in the game, I didn't use it much because I really liked the M-16 and M-4, but when you go to the SCAR you feel the difference, the game gets so much easier. CQC is cake with the SCAR which is one of the few knocks on the M-16, and Scavenger is almost a must have when you use the SCAR, but it is so flexible for long range and close quarters stuff, and doesn't need Stopping Power to get kills so you can use your Hardline or Cold Blooded. If you're not Sniping or using the Riot Shield there is no reason not to use the SCAR, hell sometimes I use he SCAR with the M203 which is a perfect pairing for Scavenger, throw Danger Close on the class and go to town with noob tubes.
As for secondaries there are a few quality guns, the M93 is a pocket M-16 and is just a beast best machine pistol overall, though if you want something for CQC the G18 is pretty ballin', nice clip size, damage, and rate of fire, though it loses its effectiveness beyond close range which isn't a problem for the M93. Shotgun-wise I haven't been able to use the 1887 outside of picking it up because I had to stop at level 66, but the AA-12 and Striker are beasts for room clearance and general CQC. I like the Striker a bit more because the larger clip and you can reload shells at will and the rate of fire is based on how fast you can shoot. I really don't see any use for the normal pistols other than a knifing class, though in MW1 I often just went pistol only because it was just incredibly fun and the fact I have a very fast trigger finger and can ADS with pistols like its second nature so when I do get my Xbox back I'm going to work on getting a Tac Knife and going to town with some pistols.