Allow infinite walls, 2 pages of messages are not enough for people who prefer not to delete but keep history. You can easily delete messages from your database after several months or a year. You already support 2nd page, so the current limit is only artificial.
Don't allow enemies to delete messages from your wall. Only player should be able to delete messages on his own wall - his own or posted by others.
The list is kept short to support lower end phones... any should be able to delete the post they made, the person who posted in the owner of the comment