So, here are my questions:
1. Am I crazy? (Am I just anthropomorphizing, interpreting Echo's behavior of needing a buddy now to get something I want?)
Yes, you are crazy. We all are crazy for this amazing breed
2. Am I taking a bigger risk getting an F1 than another F2 or Maine Coone? I have seen and handled an F1 we are interested in that by all appearances, could fit the bill.
I love my Loki, it took two years for the hubby to love him and lots of fights.. They are crazy and a bit destructive if not played with enough, and even if they are

He loves like no other cat I've ever had, I adore him
3. What can I really expect and what type of obstacles might there be? I can think of health issues (same with any cat but a bigger financial risk, if you will, with an F1; interaction / dominance / bully issues; stress / litter issues (but didn't have it with visitor); any others?
Obstacles: playing nice with others, really stinky poos, eating things resulting in 8k of surgeries, peeing all over after a move and ruining beds and couches. Lots of patience necessary. They do not like change. He used to not be scared of visitors, but he was highly socialized in an office setting from a kitten. After a year I have changed jobs and can't bring him to work. He is getting more and more skittish of strangers.
Assuming I'm not crazy...
4. What is the market price for a good F1? I know it's $10-15K but are there more specifics - e.g., this is what you should expect in a $11K cat vs a $15K cat?
Loki was $15k. I think he's a good one

Just make sure the breeder socialized the kitten. This will be the biggest difference in temperament.
5. What health guarantees should I expect and what tests / proofs should I be concerned with?
Make sure it is a respectable breeder that you can rely on. When I had the obstruction scare with Loki, my breeder was very supportive. I was terrified and they helped. You need someone who is there for the cats and not just the money. It makes a huge difference in relying on just the vets opinion. They've probably seen it all and can assist . My breeder was able to give good advice to need when I felt panicked.
6. Any other consideration
Gods speed! Be patient and post photos!!