When I first got on Twitter in 09 hashtags actually meant something. They were simply used to make it easy to search for tweets about certain topics. As twitter has become more popular and more young people have begun to use it the hashtag has gone downhill. The younger crowd began using them on Twitter as sort of an afterthought to their tweet. Since they just made them up as they went along they were meaningless. Now people use them on other sites where they make absolutely no sense.
I always thought you could search hashtags on Facebook as well. At least, I have in the past. And I know that they mean something on Google+ by making your post searchable, and adding to the "Trending" timeline they have. Otherwise, the only times I use them are on Twitter and Google+. Then again, I haven't been posting to FB too much before I got my Lumia (I hated the Android FB client, but I actually like the WP8 MS client, so I've been using it more).
Surprisingly, yes. I wouldn't even install the Facebook app for Android because it would turn on my GPS at random, and eat up battery finding my location, something I personally never use with Facebook. Then the interface was just their touch site done for Android. It wasn't personalized or anything. Yeah, all in all, the Facebook app for Android was a downer for me, and I never used it. At least I can bear installing the app on my WP8 device.