easily installed , but a bit hard for setting

easily installed , but a bit hard for setting, i have insert my facebook App ID on this plugin

my problems have two :

1.there were error message under FB comment box :

WARNING: Facebook’s servers can not catalog the XXX URL ,

more details on facebook’s page :

a.Critical Errors That Must Be Fixed
Bad Response Code URL returned a bad HTTP response code.

b.Errors That Must Be Fixed
Missing Required Property The ‘og:type’ property is required, but not present.

2.this plugin seemed not to replace default WP comment, and i have no way to remove default WP comment block