If a bike has Campy, does that mean the bb is Italian threaded? or can it be English threaded? A friend has a 2000 Litespeed with Daytona and wants to replace his double with a compact. I'm debating between suggesting to him go with Campy Centaur at $400 or something like a FSA SL-K carbon crank which is half the price or even more, $200 or even less. I don't know what his bottom bracket is threaded.

Only if the frame set is Italian made, Litespeed would use British standard.

Campag sells a lot more Brit stuff around the world than to Italian builders at home.

You can get Campy cranks for a lot less than $400.

https://www.ribblecycles.co.uk/pp/roa...sets-Road/CHAR

He could probably get an older (used or new) crankset to use with his existing BB. I assume it's square taper for a 2000, but not sure.
Depends if he wants new bling, or just something functional with lower gears. I bought a NOS (New old stock) Veloce compact for $45 or so (without BB)

The $400 is the Campy Power Torque, carbon crank.

Campy bottom brackets come in both Italian and BSC (ISO) threading. A Litespeed will always be an ISO 1.37x24tpi R+L thread. If removing his old Bb for him, don't forget that that the right cup has a left thread.

Well, t here is a wide range of options. If he wants to spend $400, he certainly can. But I hope he knows that's near the top end of prices.

The Power Torque Cranksets are not differentiated Italian or English. It is only the relatively inexpensive bottom bracket cups that differentiate between Italian and English threading.