Every post has comments, reached by the Comments link at the bottom of it. Anyone who can see the post can comment on it.
That is the whole feature. There is no voting on comments, no replying to a comment, and no nesting — it is a conversation under a post, in the order it happened.
Why there is no like button
A like is a number, and a number is a thing to optimize. This place does not have one, anywhere, on purpose. If something was worth your attention, the way to say so is to say so.
Removing one
Remove appears on a comment if you wrote it — or if it is on your post. Being able to clear something off your own page without asking anybody is the point.
You will hear about it
When somebody comments on one of your posts you get a notification. Email is off by default for every kind of notification — you can turn it on, per event, under Settings → Notifications, and turn it off again in the same place. The only mail that arrives without you asking is confirming your address, resetting your password, and one welcome message when you join.