Beto,
Was trying to PM for your query.Here are the responses.
a) You would send the xerox copy ( of relevant pages in passport ), along with photos and other documents to CIC Mexico through mail. OB 348 talks about this: http://www.cic.gc.ca/english/resources/manuals/bulletins/2011/ob348a.asp
My advice to you is to use reputable courier service.
b) On receiving your documents, CIC would send you COPR document confirming their approval for permanent residence.This will be sent to the address given in PA application forms. Sometimes CIC can ask you to confirm this address.
c) Once your wife receives COPR document in hand, she can take the document, and do the landing procedure. See my signature on landing forms. Please note that some of these forms may change before your wife actually lands.