oh! i didn't see that, just read it. 
agreed about the tank level, though i liked the bot levels, they were interesting. all about timing. 
online is getting better, usually 4-5 people per try. remember this didn't sell well at all the first week (even not considering the history its older brother made) so there weren't many out there. 
funny, i usually ditched at least one of my starting guns as soon as the level started. that way i knew i had a steady stream of bullets coming throughout the level. 
i got past that sniper level, only through persistence, and getting a chance layout where all were easy to hit. 
agreed about the iron sights thing. personally i am annoyed that COD makes it such a difference to use them. most of the time i just shoot more rather than use the sights.