Go to www.themodernwarfare2.com you will find all you need to know
You can get some by completing challenges,perks,weapons,or killstreaks
Some emblems and titles are complicated to get or you have to be a certain prestigeto earn them.
Well you need to sign up for Call of Duty Elite In order to get the Double XP Title/Emblem. It's free!
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
No you don't lose your emblems and titles
Yes you can
You need to be more specific on the "Diamond" there are a few emblems that look like Diamonds Here is a link to the list of emblems and how to get them: http://emotionalninja.net/modern-warfare-2-how-to-get-titles-and-emblems/776/2
heres one with emblems and titiles http://www.se7ensins.com/forums/modern-warfare-2-discussion/156442-callsigns-and-emblems-pic-list.html and heres how to get them http://www.se7ensins.com/forums/modern-warfare-2-discussion/156444-callsigns-and-get-them.html
Unlock the challenges for them.
Complete challenges and level up.
Your face thats the answer
to get all emblems you need to complete a certain of challenges for each weapons, which is really hard...
get 1500 kills with each guns
Because, you will actually gain more titles, emblems, and challenges. Why not?
no everything is reset except titles and emblems