Exclude recent posts from specific forum(s) from last/recent topics widget?

My forum: http://www.beadthrilled.com/

I use the "recent topics" widget on my portal and it shows very nicely the last post to any topic from any forum.

One category (marketplace) is dedicated for swapping/selling by members. It would be very convenient if I could exclude/switch off certain forums/categories like this marketplace in such a way that its new topic/posts don't show up in the "recent topics". Members however, should still be able to visit/read those forums.
Sometimes "recent posts" only shows topics from the sales/swap section because of the activity in there.

Additionally, I also have auto-subscribe on for groups. Since I have 1100+ members manually adding members to specific user groups is too time consuming, next to frustrating to members too. However some specific members should not be auto subscribed to certain group/levels despite their contribution in posts. How can I exclude them from groups without having to manually administer groups instead?

Any help is greatly appreciated!

Both the things are not possible.

Some code perhaps to simulate a similar result?