1.Can my fiance come to Canada on a visitors visa and we get married then or should we get married before he applies for a visitors visa?
He can come to Canada on a visitor visa and then get married. If you get married and then apply for a visit visa, odds are that he will be denied due to risk of overstaying and you will have to sponsor outland and wait for his PR to come through.
2.Is the longest visiotrs visa 6 months then you apply for a extension?
Yes, that is usually how it works. Extensions are always given if you have applied inland already after 6 months and usually too if you have applied outland.
3. When on a visitors visa can he work or wait till he is approved for a open work permit?
He can not work on a visit visa.
4.If he is here on a visitors visa and we send in all the first stage paper work can here stay here while it is pending and is this called the Inland?
Inland means that you mail to Vegreville and case is processed in Canada. Outland means you mail to Mississauga and it is processed there and in his homeland. In both cases, he could be in Canada during processing. Sometimes outland is faster. Inland has the downside that if he must leave Canada and if for some reason he can't come back, the application and waiting time is gone.
5. While on a V V what if anything would send him back? Is it only after the 6 months and he doesnt get a extension?
If he stays within the law, nobody will send him back before his visit visa expires.
6. So if we get married, he is here on a V V and we apply for a Inland and at the same time a extension, open work permit for after the first stage approval then what happens after that? How long will it take to be a PR?
Right now, it takes 8-9 months for first stage approval, see http://www.cic.gc.ca/english/information/times/canada/process-in.asp#perm_res
After that, he would get the open work permit and could apply for health care. In some cases, people are getting PR a month after first stage approval. In other cases it's a year. Processing time varies.
If there is something wrong with the application and an interview is required, it will delay it. Often more if you have applied inland than outland. If that happens. With inland, he would not get his first stage approval and would have to wait until your CIC office has time to talk to him. This can sometimes take a year, sometimes more. For outland, he would have to go to his home country for the interview.