Boot Camp won't work: why don't I have disk0s0 or disk0s1 partitions?
I can hardly imagine someone will have a similar problem, but if they do:

Seems like Bootcamp wants to see an EFI partition. Once again, here was the gpt show output from above:

my-MBP:~ uname$ sudo gpt show disk0
       start        size  index  contents
           0           1         PMBR
           1           1         Pri GPT header
           2          32         Pri GPT table
          34      409606         
      409640  1464477344      1  GPT part - 48465300-0000-11AA-AA11-00306543ECAC
  1464886984      262151         
  1465149135          32         Sec GPT table
  1465149167           1         Sec GPT header


As per the details in this question, i learned that the EFI partition should start at 40 with a size of 409600. To mess with disk0 (for me, the current and only disk), i booted in internet recovery by holding ⌘-R, unmounted disk0 with 

diskutil unmountDisk disk0


then re-added by EFI partition using 

sudo gpt add -b 40 -s 409600 -t C12A7328-F81F-11D2-BA4B-00A0C93EC93B disk0


I removed the -i 1 bit (setting the partition index to 1) for fear of messing with the main partition (which had itself moved to index 1). Here's the man page for gpt. 

(The above apple.stackexchange answer describes how to reformat the EFI partition. I didn't do that and haven't run into any trouble so far. Maybe i'll regret it.)

To fix the incorrect indices, i followed Rod Smith's instructions here. It's all pretty clear, but briefly:


Download and install the package.
Run gdisk /dev/disk0 (or whatever disk you're working with)
type ? to get to the main menu
typed s to sort the indices, then w to write the changes


No more Bootcamp errors. Hooray!