You may visit for up to 6 months but you may have to prove that you can support yourself while you visit. Maybe having a letter from your parents inviting you would help, just in case you get asked. I have never heard that travel insurance is mandatory but it's a very good idea to have one. If you have an accident, you could end up with a very big bill if you don't have insurance.
If you find a job while you are there, the employer would have to apply for your labour market opinion, see
http://www.hrsdc.gc.ca/eng/workplaceskills/foreign_workers/supperimm.shtml and I have heard this usually takes around 6 weeks, could be longer. If it's a skilled job, you can apply for your work permit to be processed at the same time, see
http://www.cic.gc.ca/english/work/processing.asp You could also just get the LMO and when you get it, take a trip to the border and apply for your work permit there.
If you decide to stay, if you have a skilled job, there will be ways for you to apply for permanent residency later through Canadian experience class or through a PNP with employer support. If you are not doing a skilled job, the only way would be if you qualify to apply for the skilled worker program, you could do that after a year in Canada. You can look at your options at
http://www.cic.gc.ca/english/immigrate/index.asp