Windows – Dual booting older (2011) MBP into Windows and Linux (not macOS)

I also had this problem (on a 2012 MBA). Running rEFIt's partition table tool and accepting the "update the partition table" dialog it offered fixed it for me. (The Ubuntu install instructions at https://help.ubuntu.com/community/MacBookAir4-2 do tell you to do this to resync the partition tables; but not doing it didn't seem to cause a problem at the time.) For me the only partition table change it made was to change the type of the recovery partition to Apple Boot: probably best to look carefully at what it is proposing on your system before accepting it.

1. I don't know what do you mean by where to find /etc/apt/sources.list . It's in /etc/apt/ as the path indicates. You can edit this from your terminal, I prefer using vim. sudo vim /etc/apt/sources.list, hit Shift-G to jump to the end of the file, followed by 'o' to go into insert mode on a new line and write deb http://http.debian.net/debian/ wheezy main contrib non-free. Then hit the escape key followed by ':' then 'wq' and hit enter to save and quit. (you're free to use any editor you want just remember to run it as root with sudo)

2. Kali is based on Debian Wheezy: http://docs.kali.org/policy/kali-linux-relationship-with-debian

3. When the first step is done correctly you should be able to do what the debian wiki says.