unlock at rank 41 after completing "Rival" challenge.
To get the gold cross emblem from COD4 its 1,000 kills with an AC130 but the MW2 10th is unexplained by IW and has never been leaked since IW will not say. People will say it is from completing all challenges, however that is not true. The rumor is you need to find and complete a secret challenge to earn it.
To get the mw2 nuke emblem you have to get 10 nukes OVER 9000 joke, 10
get 2500 headshots
Get 25 AC-130s
yes
There is no rhino emblem. Unless you are talking about the Ghost emblem, in that case it would be reaching 10th Prestige.
10000 headshots with snipers
The hyena...You have to get 50 kills with a RPG.
call in 25
you need to get 5 tactical nukes
Complete ak-47 veteran2
play team deathmatch and get the top score