Ikea Pax "hack" - built in questions..

Hi folks,

Look for some advice. About to pull the trigger on some Ikea wardrobes that I plan on making look built in in a contemporary style - so completely flat doors, no trims etc.

Questions/Challenges:

1. My room is carpeted, I need to take it up right?
2. Once I do - plinth or not? Its an old victorian house
3. Attaching to wall - feel it may be easier and less messy just to attach some battens to support the wardrobes as I doubt the walls are flat plus the skirting is prob welded/plastered on.
4. Anything I have missed?