I don't download from iTunes so can't help you there.
I use a piece of PC software called DVD Catalyst and it cost about £10. There are free software out there but I couldnt be arsed to look.
You load your DVD, tell DVD Catalyst what your gadget is and it will convert the DVD into the appropriate file size and type. You then import the finished file into iTunes. From there you sync to your gadget in the usual manner.
Some DVDs have special copyright protection that stops most DVD rippers from working but that conversation is for if it when