One question... Imagine that I've put an account at sell list... after 4 years, if no one has bought that account, I will lost it or it will be at sell list forever?

u'll lost only coins (if acc isn't empty), acc remains urs.
Not correct, the account with funds are reclaimed.
Are there any other ways an account can be reclaimed by the network? What happens to the account once it's reclaimed?
I don't think there are any other ways than "no use for 4 years".
Actually it is the coins that are recovered e.g. transfered to the miners account. As far as I remember the account is left empty.