(a) is there a feature to have the system notify me via e-mail if one of my answers gets edited
I do not believe that you are e-mailed when one of your answers are edited—the system is very reluctant to e-mail users, in part to keep down unwanted e-mail traffic, but also in an attempt to encourage people to visit the site more frequently.
But you are notified. As Jeff's answer here indicates, there's a top-bar notification for edits that goes something like:
You have {n} new edits. See your responses.
And in case you miss the top-bar notification (or it doesn't show up for whatever reason), you can see a full history of edits other people have made to yours posts in your user profile. To get there, open your profile page (by clicking your name in the top bar), select the "responses" tab, and filter by "revisions".
(b) can I subsequently remove my signature from the answer if I don't like the edits someone else has made
No, unfortunately you cannot. Well, not selectively. You can always e-mail the team and ask for them to anonymize your account, removing your name from all the posts you have contributed, but you can't do this for individual posts.
But you don't have to resort to that because you can always roll back edits made to your posts that you disagree with. For example, if I wanted to roll back David's edits to my answer here, I would click on the time above his name at the bottom (indicating when he was the last one to make an edit) to show the revision history:
and then click the "rollback" link on whichever revision that I want to use:
In general, users should not be editing other people's answers in such a way that they would ever want to "disown" those answers. Edits are largely intended to fix minor typographical errors, and sometimes used to fix relatively minor factual errors. In all of my time participating on Stack Exchange sites, I can honestly say that I've seen at most one edit made to one of my posts that I've strongly disagreed with, and I just rolled that one back.
