1. I have "heard" from others that some people were deported because they turned up in the month of their study completion for "wont leave Canada" reasons, so I would suggest you leave as soon as you can. Dont stay in the comfort zone of job, believe me you'll make almost equal there with part time job and you'll have advantage of going early and learning new things, to get settled. I made the same mistake, should have traveled in Dec 20 when I got the visa, now I am waiting for decision on visa file, same excruciating wait again this year. I had to arrange for funds from relatives to pay full 1 yr fees again in order to apply under SDS. If I was there, application process would be much easier and I would have got the SP extension (which is possible only form in-Canada) by paying just one semester fees. Also, I would have earned 4x my current job by working full time in the days between two courses after applying for SP extension.
2. Again, chances of visa approval are higher in Canada than from outside Canada. So after having told all the above and my own experience, make your call.