In the market for a used Toyota Prius, need assistance

So I'm a faithful Toyota owner and a very capable DIYer. I have a 1999 Toyota Camry with around 205K miles on it. I've done all my own work to the car and to be very frank it's been a very reliable vehicle. However, over the past several years it's turned into a commuter car as I commute to DC almost daily. In addition I hit a deer about a year ago and the side of the vehicle's been looking kinda raggedy. I also have a cracked windshield that has a "work order" on it that costs around 200 dollars to replace. I figure the value of this vehicle is around maybe $500 bucks and I'm putting another 200 in it. . I have on average a 60 miles daily commute.

I've been looking for a used Toyota Prius and realize that used the vehicle can be quite expensive. A used prius with low milage (less than 40K) is around 13 to 15K depending on options (in my area). Now a used one with over 100K can be 2K to 5K. What's weird is I'm seeing 200K and even 250K+ priuses for sale that look immaculate. I've also researched on the battery replacement and it seems pretty simple. I've seen the YouTube videos of the entire process of buying a rebuilt cell bank and removing your entire battery and replacing each cell. The thing about me is I tend to keep my vehicles for the long haul. I don't get rid of a vehicle until the "wheels fall off". My min requirements are a Prius with Keyless entry (key fob to unlock all doors). I would like to have the ability to unlock my trunk via fob, but let me know if that makes my search difficult. Bluetooth. A backup camera would be nice but it's not a hard req.

So I have a few questions.

1. What are the "best" years of Prius. I see there are 4 generations (1997 - 2003), (2003-2009), (2009-2015) and (2015-present). Which generation should I stay away from.

2. What's the deal with high mileage prius, should i stay away from the 200K mileage. A person who I spoke to who does prius battery rebuilds says that they can get incredibly high mileage.

3. How do priuses handle replacement of stereos etc. Is it like a regular car with a 12V system. Is it very difficult to do this in Prius. If I pick a bare model prius I might get a receiver with a flip out LCD screen and a backup camera added. I've done wiring on vehicles before with remote car starts etc...

4. I'm not really concerned about a bad main battery if I know it upfront when buying the vehicle. But later down the road if I need the replace the entire battery I understand the rebuild battery (entire) is around $1,500. However, I've seen people buy individual cells on ebay and rebuild the battery themselves. So I guess my question is does the entire battery bank go bad or do a few cells go bad first. They also have to do some balancing of the cells and I've seen this on youtube as well.

For example, I've looked at a 2005 Toyota Prius with 88K miles on it and a oil leak. It looks good overall. The person wants 3K, is this worth it?