1) What could be the documentation OP is to submit for legal separation?
Please correct me, If I am wrong with my perception.
2) I dont understand this point, how can Canada dermine/validate the marrital status of a foreign allien?
Back in my home country, proof of living together for over a period of time can be used by either partner to claim marrital status, file a divorce and demand compensation. Talaq based divorces are still practised. These are not valid by Canadian law. According to IRCC you need to provide documentation if you claim a status other than single and this documentation has to come from the home country, OP cannot just verbally claim this status.
Very recently another PR applicant here got charged for an 1 oz marijuana possesion in US, if convicted its a Class 5 felony on his FBI records with jail sentence. But according to Canadian law it is not a crime. So will IRCC not consider this conviction?