We don't have things set up yet so owners are notified when someone asks about their car. This is something we've considered.
To get the opinions of many owners, I'd check priuschat.com.
I had a Prius c for a week to review it. The questions I'm somewhat able to answer:
2. I think it's pretty easy to learn to drive it for excellent fuel efficiency. The car provides good feedback by scoring your driving style. For expert tips, check out cleanmpg.com.
3. All versions of the Prius from 2004 onwards have been extremely reliable in our survey.
4-5. My guess is not synthetic. Toyota's recommendation might be 10k miles, but you should check. Overall I'd expect maintenance costs to be low.
7. Not a great car for long trips. Rougher and noisier than the great majority of other cars.
8. I'd take him to a Toyota dealer to answer this one. He's the best judge of this.
For driving enjoyment and comfort, I like the Ford C-MAX much better than even the regular Prius, much less the Prius c. But the Ford isn't as efficient, and isn't as likely to be reliable (though the 2014 has been very good in our survey so far). It's worth a look.
All hybrids have their largest fuel economy advantage in stop-and-go driving, and their smallest advantage on the highway.
One thing to keep in mind: since your Fiat is already fairly efficient, it's nto really possible to save all that much with a more fuel efficient car. You'll lose more money in trading the Fiat than you'll regain in fuel savings.