I'm not so sure about the second question, no, but I know that some Pentium 4's run at 533Mhz I think. Don't know about Hyper Threading though
Yeah, I read this about a random P4 motherboard, shows that you could get a 533mhz one that must be running at atleast 3.6Ghz so can't be too bad...:
'Motherboard's features: Intel 875P chipset, Supports P4 800/533/400MHz FSB 3.06GHz and up'
I don't know much about FSB and that though.
Heres a list of them available on one site, might be the whole range, I wouldn't know
But basically from this, the maximum Pentium 4 speed you could get is 3.6Ghz which is really fast, the fastest available, still at a 533Mhz FSB.
The 400Mhz FSB's only go up to 2.6Ghz
I hope this helps