QUOTE(xxkasperxx @ May 15 2012, 11:34 PM)
he wants a more in-depth CMS where he can basically change whatever he wants.
The more things he can change, the more complicated it will be (both to create and use). At the extreme end he could simply use an HTML editor himself.
Would it be better to do this with a Custom CMS or something like WordPress?
Impossible to say (what on his site does he want to change? what does Custom CMS mean?). Installing Wordpress (or some other blog format) should mean less work compared with creating your own CMS.
If WordPress is the way to go, please give me a link or instructions on changing MY HTML and PHP into what WordPress can use.
My guess is that you'd have to redo the site (to the extent it's possible) using whatever instructions/tools Wordpress provides.