What crankset should I buy to suit an 8 Speed Campy freehub? I've just bought a pair of campagnolo/mavic wheels without a freewheel.
I'm finding it very hard to understand what will fit on the rear hub.

It's English thread, does this mean that any 8 speed freewheel will fit (as long as it is an English thread)? 

Secondly, what rear derailleur will I have to use (if I buy a Shimano freewheel, can I use a 8 Speed campy derailleur, or does it have to match)?

Thirdly, will this influence what front cranks and chain wheel I get (If I buy a Shimano/Campy freewheel, will I have to get a matching crank/chainset combo)?

I'm trying to understand the whole crankset picture in one go!

Here's a link to the wheels:

http://www.ebay.co.uk/itm/170802467619?ssPageName=STRK:MEWNX:IT&amp;_trksid=p3984.m1497.l2649#ht_500wt_1413

Many thanks in advance
Freewheel threading is pretty universal. You can put any freewheel which is appropriate for your drivetrain on those wheels. 

Regardless of whether you choose Campag or Shimano, stick with gear designed for one system, and as much as possible one gear number. (8 speed, 9speed, etc...)

For instance, if you use an 8 speed Campag freewheel, use 8 speed Campag shifters, chain, derailleurs, and either an 8 or 9 speed Campag crank set. You will need the appropriate bottom bracket to match your crankset. 

It is possible to mix and match a bit, mostly the chain could be either Shimano or Campag without major issues. But best to stick with one system, especially if you don't understand the compatibility changes you're making. 

By the way, those wheels are tubulars. That is, glue on tires. Were you aware of that?