No you can play co op at any time online or split screen
No only on campaign is split screen
Yes you can.
no, you can only unlock online things when you actually play ONLINE. if you use your split screen account, you can unlock titles/emblems for split screen only.
yes u can
yes there is one for 2 players online versus (no co-op) called overturn meca wars, purchased from wii shop channel.
No. You can play split-screen with a friend on versus. But if you are wanting to play online, you obviously need Xbox Live.
No, you cannot play split screen online on CoD 5.
No
Yes
you either play split-screen with a friend, system link with a friend on another consol, or online with random people or friends
Yes but it's not like the past RE5 split screen because they were experiencing problems with 'screen tearing'.