Lordaeron vs Icecrown vs Blackrock

[case011]

Hello, I'm new here and I would like to know about the differences between your realms and ratings, of course. On which realm there is a donate, do you have a cross-bg and if there is how it works and which servers are connected to it, well, having played a little bit on x7, I saw that there are huge queues, the queues are always so big?
I'm mostly interested in the arena and bg connected to the cross server?
Sorry for the clumsy English, I'm just doing this Google translator.