You used to be able to address a post to "all" to ping everybody on the thread.
I presume that does not happen now. I use "all" when I am making a generic reply to a thread and don't want it to appear that my comments are directed at the original poster only.
Regarding an RSS feed for My Comments, I wonder if Firefox's "Live Bookmarks" can use the domain cookie, so that a FF "Live Bookmark" would work for My Comments.
On second thought, don't. Bad idea. Bad idea. Bad, bad idea...