As you've already heard, the answer to most of your questions is "it depends" - on your job qualifications, your field of study and lots of other variables in your situation.

One thing to consider, though, is that in answer to your question #2, the areas where you are paid more in a job are generally the areas where the cost of living is higher, so be sure to consider more than just the salary you're quoted.

Students can, of course, work - and there is also the possibility of working full time while taking part-time classes (sometimes referred to as "night school") and depending on your line of work, some employers will even pay your tuition and books if they believe the program you're taking will benefit your on-the-job performance.

Traditional old "financial aid" is harder to get these days, and often comes in the form of student loans, which can tie you down for years after you graduate. As a newly arrived permanent resident, these sorts of loans may be more difficult to get since you have no credit record, and there is the suspicion that you could return to your country to avoid having to pay the loans back.

If you're going as a permanent resident, though, you'll be spared some of the visa "challenges" for someone on a student visa.
Cheers,
Bev