buying used Prius advice

I currently drive a '95 Corolla. I'm interested in a Prius hatchback, 2010 or after, and have test-driven some of various years, including those made before 2010.
I drive in the city, on bad roads, for work, lots of parallel parking; I estimate 5,000+ miles annually to and from, and driving for work, plus personal miles. Not high miles, but lots of time in the car and I want a quiet, comfy car for longer trips also.
I'm 5'1" and want: fuel economy, comfort, visibility, reliability, lower cost to own and quiet cabin, without getting a luxury or larger car.
I think the Two or possibly Theee would suit me; the 6-way seat is more comfy than the 8-way with lumbar that I tried on a rented Prius five. The tech stuff and options on the higher trims don't interest me. I understand I can install an after-market back-up camera. I want 2010 or after in large part due to high scores in quality of cabin materials.

Questions:
1) What details or combinations of details are most important in selecting a used hybrid, and how do I prioritize them--total miles regardless of year, miles per year, age of car, previous ownership status, having access to service records indicating appropriate care, etc.? How do I compare these variables and how much weight do I give each one?

For example, I looked at a 2011 Prius Two, 39,000 miles put on in 1 year; 9 month lease, 1 owner. Single tires were replaced twice (not sure if the same one), new set on before sale at dealer. Does the tire replacement indicate poor driving habits that might mean something else about how the car was treated--or is it largely irrelevant to the condition of the car itself? Does the high mileage (per year) mean anything, esp. in view of the frequent tire changes? I assume the new set of tires was par for the course to sell the car at a dealer. The price is down to $15,900 currently, with certification.

Another car listed today at a dealer is a 2013 Three with 34,500 miles (over 1 year, 3 months), for $19,800.00, was rental, certified. Much more expensive, similar miles, also put on quickly, but a rental--how to compare the worth of these two? It is more expensive simply because it's 2013?

2) How do I know what price is reasonable to negotiate for, for a given car?

Someone suggested looking at E-Bay sold auction prices for guidance. I looked and today there were two Prii 2013 "base" models (assuming IIs) from same seller, one had 900 miles for $17,000 and the other 12,000 miles for $13,000.00. Very different prices.

What are the most important variables--the year, mileage, condition, to bring up when negotiating with the seller, or dealer?

2) If I am serious about a used Prius from a Toyota dealer, do I take it for a pre-purchase inspection at another Toyota dealer, if I don't know any independent Prius mechanics?

3) I notice a high-pitched tone or tones in some Priuses and not others, generally at low speeds in the city. The V was the worst, at all speeds. Is avoiding this a matter of luck? The dealer I talked to knew what I meant, but didn't know if it's ubiquitous. Drivers I know are mixed in whether their cars make these sounds or not. It's bothersome to me, and might be a deal-breaker, but it doesn't seem to be a problem in all of the Prii so if I can get a car without those sounds, I'd be fine. If the car I test-drive doesn't seem to make these sounds, is it safe to assume it won't? Any knowledge about how, when, and why these tones are present would be very helpful.

4) Does the recall in the 2010-2014 Prii for the computer make any difference in considering a car, once it's fixed?

Also:
I'm considering a Golf TDI to see if it fits and for visibility, comfort and clean fuel use. But more expensive in the long run, perhaps.

I would be open to the Prius c for the potential better "fit" since the Prius seems a bit large for me, but from what I read, it's not as good a value overall as the Prius and is noisier in the cabin. Any opinions?

Thanks for any advice.