PHP-NUKE and PHP

I have a site in php-nuke,
i want to add a subdomain but wondered if i can make it in php rather than nuke?

Do they clash in this instance or cause and problems.

Also is there pre-make php templates about? i can only seem to find php-nuke templates? Happy to pay for it

Or would i be better to go the whole thing with php?

The reason i ask is i have mass errors on my site and had someone in there fixing them but it getting to the stage i need someone to be working on the errors 24/7, get ride one 1 error and 2 more appear.

any input welcome.