[electronvolt]

1. From glancing at it: this is a pretty ugly solution.

On the plus side: It's minimal and doesn't spend much time building abstractions on top of the basic lists/etc. that scheme provides. However, it certainly isn't pretty.

For instance: Things like the king & knight checks are really pretty ugly brute force solutions.

Similarly, the variable & function naming really is rather unclear and very poorly commented--some of that may be use of things idiomatic to scheme that I'm unfamiliar with though.

2. Always a possibility, I certainly don't know you. ;)

3. Some people certainly have said that before and probably will again. This is really just a personal preference thing, I think.