Alright. Let's do this one by one.
1. You must be level 16 or higher to trade other players. It appears you are level 15 and must complete a class change. You should have received an pop up quest to see a class master to complete this change. You'll have to do a few more steps (depending on your class, speak to an NPC of some sort) and then speak to a class master to upgrade to the next level.
2. It looks like you may have a corrupted file. When you open the launcher (using admin mode) click "Full Scan" once it is finished loading. This will check and correct any corrupted files. If that doesn't work, uninstall and reinstall the game, with admin mode, and have GF pass through your firewall and antivirus settings.
I hope this helps a little.