Plutonium

Restart your client, if that doesn't fix it allow plutonium.exe through your firewall.

Your language files are trash, get clean files off of steam.

Where did you download mw3 from? If you downloaded a shitty repack delete everything and follow this guide to get the game from Steam. If you already downloaded it from Steam, try verifying integrity of files.

own win 8 antivirus

WeeDStaRRR maybe whoever runs the server shut it down?

WeeDStaRRR piry doesn't work anymore. https://forum.plutonium.pw/topic/2819/how-to-install-update-plutonium-t6

WeeDStaRRR /moved
All weapons can be unlocked by typing the command

unlockall

into the ingame console (you can open the console with the tilde key).
Camos -> https://forum.plutonium.pw/topic/3810/release-mp-diamond-camo-unlocker-10-cac-slots