It is telling you how many notifications you have. For example, right now my tab shows Facebook (4) because I have 3 Notifications and 1 message. Hope this helps!
it means that the person is not actually using facebook at that time they are on a next site but their still signed in facebook
a
Wall
That is how many new articles have appeared in your news feed since the last time you went to your home page.
I think it is the number of new notifications you have.
It's the number of notifications you have. Check that it matches.
It means the person you sent the message to - has seen it.
It means the person you sent the message to - has seen it.
If you mean: 1, 2, 4, 8 and 16 then the next number is 32
The number next to your profile is the number of years that profile has been on xbox live.
I am not sure what you mean by a heart notification. If you are asking how to make the heart symbol on Facebook, you use this < and put the number 3 next to it (no space). <3 will print out as a heart. If you want a thumbs up sign, use open parenthesis, the letter y, and close parenthesis (y).
The phone number should go away - just check every-now-and-then. :)