Toughie, I feel these fasts or deprivations are a matter of personal conscience and it is up to you to make the call. From what I understand they are meant to be a time of reflection and to bring you closer to your God - Maybe you could just change how you use the site, don't tag or PM, just answer questions to be helpful to other people. My own view is that I don't think your God wants you to make yourself miserable just make a bit more time for other people and your reflections.
No, it's not. Its a question-answer site. People can and do make friendship here, but that's a secondary thing, unlike other social medias. Primary function is to be a place for people to ask for and give advice