Hello:
I have been playing Fantasy Battle for about 20 years now and I tell my oldest son how Chaos use to be and he say they sound so much more intresting then they are now
If I am remembering correctly Chaos Knights in the old days – miniature wise – are just Warriors mounted. If you look for the old Chaos warriors from around the 1980's you will find what you are looking for.
And the mutants you are refering to are the Chaos Thugs! they were the grunts of the chaos force, those and the Beastmen which were just mutants of various beast types. It use to be:
Chaos Thug or Beastman – a basic guy beginning to start with
random mutations
Chaos Marauders (in the Warhammer Armies Book) – the in between stage, better armor and such
Chaos Warrior – at this point you can but dont have to pick a patron and mutations continue
Chaos Champion – Depending how good you are you begain to feel the preasues to pick a patron and further mutations happen.
Chaos champion of (whom ever the champion picks or remain undivided)
Chaos champion begains to build a following
From here you go to either a Deamon Prince or a spawn – driven mad by the insanity!
If you can find the REALMS OF CHAOS – Slaves to Darkness or REALSM OF CHAOS Lost and the Damned – they will fill in a lot of gaps for you.
You can find these models but the pricing is going to be night and day, I got lucky and won several auctions for the Thugs and picked them up for about $2 USD each a while ago.
Here is a links, you will want to got to the Realms of Chaos section and have a look:
link
Because GW has set the standard to the industry you can find many vendors who make very similar miniatures like these now a days.
I will see if I can find the name a post them later for you.
Have fun!