1. The employer needs to apply for a labour market opinion from Service Canada. This is basically a document stating that he has advertised the job for a certain period and is offering market wages but has not found any Canadians or PR's who are qualified and interested in the job. If he gets this document, he can send it to you and you use that to apply for a work permit for the job. Your work permit would be tied to that job and that employer. If you want to change jobs, the new employer has to apply for a new labour market opinion and you would have to apply for a new work permit based on that.
2. Some countries have working holiday / travel&work / youth mobility or other such exchange programs. To find out if there is one in your country, contact the Canadian embassy where you live. There will be age restrictions but you could get an open work permit of 1-2 years which would allow you to come to Canada with a work permit and work anywhere.
3. Apply for permanent residency under the skilled worker program if you qualify and you can come to Canada and work, live and study unrestricted.
The Canada immigration website is at http://www.cic.gc.ca/english/index.asp
