1) Can we have thread notification actually give thread notifications ?
The feature works for me. I have to assume there's something specific going wrong on your end.
2) I'm browsing with mozilla firefox...
Currently the percentage of non ie browsers (<1%) is so low that any effort spent accomodating them simply doesn't make sense. There's much better places to put in time.
3) Can there be an option to turning off these annoying floaty yellow boxes whilst browsing through thread listings ?
I'm not sure if the popups can be turned off or not. I'll discuss it with the other mods. I'm not a big fan of them myself.
4) Is it possible to have the back button skip back to wherever
That would be nice but I think any attempt to make the back button forget pages would necessarily be hack-y. I'm not even sure it could be done.