I would suggest you read the full white paper, as well as Satoshis own emails and posts. He makes a lot of sense in them and it's often not as hard to understand as some may want you to think it is.
"Performance" can be a good barometer, but it doesn't show which coin is Bitcoin unless you define "performance" by adhering to the fundamentals Satoshi wrote about in the white paper and explained elsewhere. A lot of anti-Bitcoin Cashers would suggest that a high price is or popular support is "performance" enough, when that actually has nothing to do with it.
Yes, we'll see what happens. My hope is that both systems endure on their own merits, but that Bitcoin Cash lives on known by most simply as Bitcoin.
I hear you. I have read the whitepaper and some of the emails, but it starts to fall apart for me when I get into some of the non-basic cryptographic concepts and economic theory. I don't consider "high price" any sort of indicator at all though. It's more of a red herring. I like Vitalik Buterin's somewhat recent series of tweets that question whether the high market cap is actually deserved. Bitcoiners should be asking themselves the same questions.