I have my own mod folder and config files for eveything, thats what I did. Just asking this, as I saw that DHF has emptyied the various additional expansions' config files and transfered the codes to text.csv. Everything is made more smooth and efficient in DHF. So just copy-pasting DHC into a mod folder, then putting DHF on top of it should be the basic way to make your own config base to modify.Config files:
Best leave DH alone. Don't change any DH files.
Just add your new stuff to the bottom of the individual files.
And mark it for your mod so you can find it easily.
............
If you have to change DH config files, then make sure the xxxxxxx; are all the same as the rest of the file. Best to check in OpenOffice Calc as you will see an errant x very quickly, as it will be in the wrong column. Save as csv without any problems.
EDIT:
Overall, for everything, I would say the best guide is to get WIF2 and see what FT did and how he did it, and do the same as him.
WIF2 is probably the best guide