For FSW, additional documents include ECA (not required for CEC unless you got EE points for it), proof of funds (in my case, bank letter, 6 months of statements, and T4 and NoA), and reference letters and pay stubs if possible from all employers, Canadian, home country, and foreign that you got points for. For us, that was 6 jobs for me, and 2 for my partner.
If, God forbid, our application is rejected, I will take off my current job, lower our funds to zero, and take our chances with CEC.