Is there anyway in which you can mark certain posts which are of interest to you so that when a reply is added that you get say an e-mail notification or you can check when you come on? Becuase sometimes when you don't visit for a few days, even just one day, sometimes, you find it hard to find some posts.

P.S I know you can request reply notification if you start the topic but what about if you just contribute and want to be notified of further contirbutions. Am I asking too much?

The red cups show when new posts are made, so that's pretty easy.

As you said, if you start a topic, you can be asked to be notified by email when somebody responds to your posts.

Other than that, if the subject is important enough to need that answer or response, I suggest you check the particular forum on a regular basis. Sounds like a sensible plan to me.