When adding a new theme/skin
 

If I have installed a few hacks and I want to add a new skin do I have to replace all of the code or just certain sections? The reason I asked is because of a hack I installed and with the new theme it seems to be still working.

If certain sections which sections do I need to go back over?

Depends on how you add the theme, and its custom templates.

If you use a system like this assuming your new theme doesnt have any custom templates.

-Default Theme (not usuable) (make all template edits to this)
-- Usable Theme - Make no template edits
-- Usable Theme 2 - Make no template edits

I thought you could only add it one way? The last thing I wanna do is mess up the default one as thats the one I have been working with and now I have just added 3 more skins and I want to add all the mods I put in.

Here are a list of mods:
ibProArcade - 2.5.6
Members who have visited the forum - 4.32
vbBux / vbPlaza - 1.5.8
vbBux / vbPlaza - ibProArcade Addon - 1.0.0
vBShout - 2.0

I might have added sone other things but they are all just texted added to the templates