Removing the DPF IS a problem - the particulates that the DPF is designed to trap will now be expelled into the environment.
Please don't do this...
I suspect the insurance companies would take a dim view of this and treat it as a modification as well. On the basis they will take any chance they can for a few quid.
Diesels are more expensive to run = bollix. They only become expensive when they are used as run arounds. A diesel that only covers 6K a year on a motorway will be cost benefical vs a petrol doing the same (with today's technology), change that 6K to town and it's a different matter.
That's interesting. I was looking at a diesel (more or less because for most MPVs there's little choice) and was slightly worried that I was being fooled by the pump price. We live rurally, so pretty much every time we use the car it's 7/8 miles min.