No. You have to prestige.
All your guns, attachments, equipment, perks, level, classes, and challenges reset.
no everything is reset except titles and emblems
No, all your guns are reset to the same as you were when you were level 1. The only thing you unlock when prestiging is emblems and titles.
Prestige tokens are earned every time you prestige. When you reach Level 80, you will have a chance to prestige and earn a prestige token, however, prestiging will also involve losing all your guns, attachments etc. apart from your stats, emblems and titles. You will also be reset back to level 1. When you reach level 80 again, you have the chance to prestige again. You can prestige 15 times, (the equivalent of level 1200).
Everrything resets except for titles and emblems. So yes.
You lose all the weapons you've achieved and you have to earn them back. You unlock new challenges, embles, titles, and more Custom classes. The highest rank Prestige you can get to is 10. After entering prestige mode, you are reset to level 1 in 1st prestige with a different emblem than the default one.
To reset your stats you must be Tenth Prestige Level 80 and have a prestige token.
When you enter prestige mode, you reset your rank, you'll have to earn everything from weapons to perks to challenges. Titles and emblems are not reset though so you can keep them. You get a new challenge group called "Prestige" which can earn you some cool titles
You can obtain new titles and emblems but that is all, everything else such as weapons and challenges are reset.
It only resets your guns, challenges, gun unlocks too and puts you back to level 1. You keep all of your titles and emblems
No, you cannot reset your kill/death ratio in Call of Duty: Modern Warfare 2, nor any other of your online stats.
No, unfortunately. When you prestige, you lose everything but your titles and emblems. Luckily with Modern Warfare 3, they have implemented a system that slightly takes the sting out of prestiging. Everytime you prestige, you are given a prestige token. With this token you can use it to give yourself 2hrs of Double Experience points for either your weapons or levels, some titles and emblems at certain prestiges or you can unlock 1 piece of gear in the whole game. Whether it be any primary or secondary weapon, a perk, any lethal or tactical grenade or a deathstreak. And the best thing is that whatever you unlock will always be unlocked for everytime you prestige after so you do not have to unlock it again, except for the double Weapon/Level XP tokens, which expire after those two hours and you have to use another token to get them again.