turns out there's an on site reply notification - go to your profile, click edit and turn this on:
Reply notify: ON by default (notify you if someone replies to your comments)
About email, I'll try to investigate further
le edit: There's also an option to bookmark threads that many people forget about - simply click on "Mark" just beneath the thread title and it will be accessible via your profile.
Especially handy if you're following certain leagues (125fps etc, so the thread is at your hand even when it's not on the frontpage)