1) Sponsoring a spouse does not need/allow a co-signer. So this section is Not Applicable to you.
2) Not sure what you mean by Part 2, there are forms for the sponsor and forms for the applicant being sponsored (your husband). The applicant should provide all the information for his section of the forms. If one of you is better at paperwork, there is nothing that says you can't help or even do it for him, but ensure he provides the information and understands the questions correctly. Absolutely do not guess anything.
3) You should change your marital status, it can be done concurrently, but it is easiest to get it over with first.
4) If an interview is required, he will be asked to go to the nearest Canadian embassy, yes.
5) That depends on what office is responsible for his nationality. See here for processing times:
http://www.cic.gc.ca/english/information/times/perm/fc-spouses.asp#europe