Hi,
The image in that template does not have a fully qualified url, it would need that to work and then still some email clients will block images.
I do not currently have a good way to make the default pre-selected on the newsletter signup options. At some point I will probably implement that.
The description renders in a div inside an li, there is no limit on the size, you can adjust layout by css.
There are delete buttons for newsletters are you saying they don't work for you?
Users not shown in the member will show up on member list for admin if he searches on the user name or email. I do not get any errors updating a user that is hidden. Maybe you mean a user that is "deleted" in the case where site settings is configure dto not really delete users but just flagg them as deleted.
Hope it helps,
Joe