Well the day came and passed, and it all went quite smoothly. I was told I am "competitive" for the positions I applied for, and barring any hiccups in the medical process (the doc later said I'm fine and there shouldn't be any), I could be off to basic training as early as the end of August

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You can put up to three job choices on your application. Many people (including myself) mistakenly assume that the choice you put in the first slot will be given priority, but my interviewer told me that they are all lumped together during the consideration process. This is why I had him remove me from consideration for the combat engineer trade. I only put it down to fill in the space.
After you send in your application, you write the Canadian Forces Aptitude Test (CFAT) to determine if you qualify for one or all of the positions you applied for. Then, after your interview, they determine which position you are eligible and most competitive for, and will more than likely give you a job offer for that position after everything has been considered and processed. The military is hurting for personnel, so as long as you have half a brain and they think you can do the job, you're as good as in. At least that's what I've heard from people who have served or are serving. It's during training when the real weeding out takes place.
[edit]: Oh yes, you said you're considering joining up after you get your degree? I assume that means you'll be applying for a direct entry officer commission then. Everything I said still applies, but after your interview, your application gets sent to an officer candidate review board. I'm not sure how many times they sit per year, but you should be prepared to do a lot of waiting.