First of all you will need to reinstall the chroot, id suggest reinstall everything, get a fresh start. I always thought you shouldnt edit the /etc/passwd file by hand as it might break thing. Anyway there is a youtube video that should fix your apt problem or ive read that this works but havent tested it.
deb [trusted=yes] http://http.kali.org/kali kali-rolling main contrib non-free
#deb-src [trusted=yes] http://http.kali.org/kali kali-rolling main contrib non-free
deb [trusted=yes] http://security.debian.org/debian-security wheezy/updates main
Not sure about the arpspoof specific problem but i wouldnt jump to purging packages so quickly
Also im no mod but i believe this belongs in the general questions section ;
Good luck