is this a genuine guaranteed dell original adapter?
Yes, this is dell genuine adapter.
My dog chewed the section that plugs into the wall. Do you sell just that part of the power cord?
Yes. You can buy only power cord for your AC adapter.
It is hard to say which one you need as you didn't specify your laptop model.
This is a brand new AC adapter.
Unfortunately I am not able to answer your question. You should call our customer service representative on our Toll Free number (877) 431-8738. Note that our working hours are from 10am to 6pm EST from Monday to Friday. Please be ready to provide your order number if possible.