item_group and item_subgroup sorting questions

[Xtreme]

Hi,

Im working on a market project and i created a currency for that...
I have 2 categorys...one is with recipes of what you get for credits and one for recipes how to get credits.

I have different versions of the "exchanger" (mk1, mk2 etc)
mk1 recipes are: 1 item = x credits
mk2 recipes are: 2 items = x credits
etc

How can I sort the group? I want it to display mk1 recipes first, then (if possible, a break row) mk2 recipes etc...

regards

PS: All the "item to credit" recipes are using my "credits.png", is there a way to display the items instead without creating a currency for every item?