Every post has user box at left. That contains "2,682 posts since
Oct 9, 2001".

Could you please consider removing it? It's a useless information, cluttering the page, making it less readable. It's easy to confuse with date of the post. If anybody is ever in that, they would mouseover and check the popup.

If anything should be there, it's actually the post info.
I would move the post metadata there:

• date of the post
• whether it's a question (a questionmark icon?)
• wheter it's answered (Check icon, like stack overflow has)