Is it possible to download somewhere :serendipity_syndication_plugin

I deleted it accidentally. I did make a fresh install in another map but cannot fid it there. It is not possible to delete my original weblog, ist has 3000 unique visitors everyday. Anybody ideas? Where to download the plugin or ...

When i use the register tool all users can make new entries. I don't want that. Only visitors who are registered may leave a comment. Is that possible.
I don't want registered users in my admin, they may just reading the blog and leaving comments.

How do i do that.

Regard,
Renegerz