1. You cannot start the application under spousal sponsorship as marriage certificate is one of the very important documents to be submitted. This will help to convince the officials that your marriage is genuine and your eligibility to sponsor depends on this. If you were part of a conjugal relationship it would have been different. I would suggest, get the documents ready and wait till you get your marriage certificate to proceed.
2. Visit visa at this point might make sense, as you are not married. If she got good travel history and no ties in Canada, it might work. But from my experience, if you apply after your application it will get rejected. The officials will think that you are trying to get her in to Canada as you cannot wait till the sponsorship is done. Try applying but what I would suggest is ask a lawyer before you do anything.
3. If you are a PR it is advised to reduce travel till you get a confirmation of sponsorship. It is always advised to show proofs that you are staying with your wife and are in a very convincing relationship. This helps your application. My wife is a Canadian citizen and she moved here for a year to India after our wedding. We have enough proofs including photographs, rental contracts, investments etc to show that our relationship was a genuine one. This was advised by our lawyer. But I have heard that there is some difference with a PR and a Citizen in-terms of saying out of Canada. Please check this.