you configured your extensions in Freepbx as PJsip right?
In yours, this would show 701 instead of 5001 obviously.
EDIT: for CsipSimple it should work as chan_sip or PJsip, but for my ATA devices I had to configure them as PJSip or they would not register.
But yes, I would start over, because the CRITICAL AMI error should not be happening, and could be related.