Help with facebook chat on iPhone?

It does tell you if your friends are on-line. Active and on-line are technically the same thing. If your friends have their chat set to invisible, then they may be on-line, but facebook won't tell you that they are. If it shows that they're active, it means that they have their chat turned on, and have recently used facebook in some way. The regular facebook site uses the same information. So, it's possible someone may be sitting on-line, but they won't show up as such, because they simply have facebook open but haven't been active. You'll run into this issue on the website as well.

I was also curious about alternatives for Facebook chat. When I found the Facebook messenger and read the product description, it said that message could be sent right to your and your friends' phones. If this is true, it means the Facebook messenger is trying to replace the traditional text message, similar to the purpose of iMessage. Having said that, the online/offline status of a contact is irrelevant, as they will get the message when they sign in to Facebook, just like they would get your text the next time they turn on their phone. In any case, it's accessible, and it's free.