From what I see/read, we're talking about a potentially game breaking glitch here. How can you certify that? True, it's only really game breaking for very very wide setups, but still it is a glitch. Icons should not be as big as they are on widescreens.
Game breaking is debatable. I will agree its definitely annoying for TH users, but so is say the health going on the far side monitors rather than the center. I do believe that they should fix it but its definitely not grounds for decertification. Oh and the feature can be disabled in the options menu.
Options > Multiplayer > Game Instructor
90%+ of people will want to have it disabled anyway especially those that have played the original L4D. It is very annoying even when playing 4:3. It's basically teaching newbs how to play an FPS game with popup messages like "You should press R to manually reload your weapon!" or "Press Crouch to duck!" or the one that we are talking about which is basically "hey dumbshit come pick up a weapon."
On:
http://img403.imageshack.us/img403/9396/11212009084429.jpg
Off:
http://img403.imageshack.us/img403/5600/11212009084453.jpg
As for the Crosshair try out
cl_crosshair_thickness 1 (def: 2)
cl_crosshair_dynamic 0 (def: 1)
in surround to see if that makes it any better.