msn, facebook chat - u can install palringo, it is free and works over wifi
facebook - use ur hotspot browser and point it to m.facebook.com or x.facebook.com
app store - sorry, u need BIS for this
mate, that happened to me, i brought my bold unlocked from thailand and i put my o2 sim in and thats what happened. So, i went to o2 and got the simplicity sim for only �20 a month and i get 600mins&600texts and "unlimited blackberry" which allows you to use apps on blackberry.
any other questions pm me and i'll try my best to help