Do 你 think I should un-fan all those people on this site who never fanned me back?

Honestly, like 你 said, that's up to you. Personally, I wouldn't but, like, that's because I'm too lazy to do so and don't really see the point. I don't really unfan people unless they persistently bother me.

Frankly I've always seen fanning as less of a friend thing and 更多 of an, 'I like the content that 你 post/I share the same interests as you' type thing.

It depends on how 你 look at it. If 你 think of becoming someone's 粉丝 as "friending" them, then maybe 你 wouldn't want to remain their 粉丝 if they didn't reciprocate. But others (like myself) 粉丝 people because they like their contributions 或者 agree with some of the 评论 they've made, so it doesn't matter if they don't 粉丝 me back 或者 even if they're no longer active here.

I personally wouldn't bother as it would take up time I don't care to use. If 你 feel strongly about removing someone who didn't 粉丝 你 back then be my guest. It doesn't matter to me in the long run. So I am in a similar 船, 小船 as Flicker.

It's up to you. I wouldn't do it as it's a waste of time and energy. I never understood the point 或者 value of adding as a 粉丝 here. It's not like 老友记 get extra access to privacy 或者 something. So, I just 粉丝 people if I have enough respect for them. And if someone adds me first, I usually add them back as an act of formality 或者 common courtesy. The whole add as a 粉丝 thing is nothing but a boost of ego here 或者 sense of security/insecurity. The blocking system is somewhat useless too.