Yes, no matter whether you've prestiged or unlocked the guns, using them from dead enemies and teammates will continue working those challenges regardless of you unlocking the challenges. You can prestige safely and know the challenge will not start from zero.
get 50 silenced weapon kills after you prestige
to get titles and emblems on modern warfare 2, you have to complete the challenges in the barracks, but for some you have to prestige
Boost. Or do challenges :)
Yes
Because, you will actually gain more titles, emblems, and challenges. Why not?
You have to be on prestige and complete one of the veteran challenges for it.
theoretically you are capable of unlocking all titles minus about 3 titles per weapon (both primary and secondary). the reason for this is that you cannot start working on the 'Veteran' and 'Master' challenges until you have prestiged. In addition to these gun specific challenges there is also an extra section added to the challenges in the barracks under the title prestige. The PRESTIGE challenges which are mostly killstreak kills and stealth,stun related challenges for which there are 15 challenges. MOST IMPORTANTLY, is the fact that master, veteran and prestige challenges are highlighted in green indicating that they will not reset should you prestige further.
Yes you do, but not your callsigns and emblems!!! =]
You work for it by killing and doing challenges not hacking.
Complete challenges, rank up, prestige, and have fun
You need to complete all of the Prestige challenges (not only the ones labeled prestige challenges but the weapon veteran and master challenges as well), probably the most time consuming challenge too. I am a tenth prestige level 70 with all of the "Prestige" challenges done, but don't have the symbol. Who is going to get 1000 multikills with the Javelin anyway.
Complete all prestige challenges. You must be prestiged at least once.