Dom you lucky fella, nice bit of kit by the sounds of it.
Firstly I know nothing about Crenicichla (except there beautiful looking fish) so I'm not sure about adding peat to the sump. Although I have heard of other guys doing it. I'm not a pro on sumps and media but having got hold of one a while ago I did a lot of reading so know a bit.
Where is your tank drilled? base or up top? if its the base then cool, if its towards the top i think you'll need an overflox box.
Any idea what return pump it is? Has that got pipework with it? If not take it with you to the LFS and get some piping, it's not too dear I got about 5ft for a fiver.
I have a sump running on my 6fter. I got mine 2nd hand and it came with sponges and bio balls. I read up quite a lot on best things to use in terms of media and the best thing to use in term of value for money and effectiveness is scrubbies, you know the things people do washing up with? not the wire ones but the plastic ones. I went to the pound shop and got a load for a tenner, and I mean lots and lots. There meant to be the best bio media available on the cheap.
Scouring pads are good too as long as they haven't got any writing printed on them or anything else that could leach out nasty chems.
I've been running scrubbies, sponge and bio balls for ages but one thing that i recently only started doing (as per advice from grandad) was to have a filter sock over the inlet pipe to the sump and to use "PURA PHOSLOCK", I'm not usually one for chemicals unless theres a problem. But a little bit of this gear in the filter sock has done wonders for my water parameters. It is expensive but you only use very little and its lasts a long long time.
Get some pic's up of the kit if your able to?
Hope some of that's of use mate.
