chat FAQ for facebook for ipad app?

[Asks some questions]

on the ipad fb app the chat part is split into two sections, offline and online i assume? but the upper part of the list, the people on it change and swap out every once and awhile. do they just completely log out of fb or what happened? and when their pic shows but no dot or anything next to it does that just mean they arent on chat? and do u always get responses because sometimes i find that i only get a response every few messages.