Hi,
As far as I know (I'm no expert and am too a fellow student just like you looking forward to go to Canada for higher studies),
Once you leave Canada immediately after completion of course, without securing post grad work permit, then you won't be able to come back,unless you re-enter as a student or find some similar routes. So, before leaving you must definitely get your PGWP( most probably with a muti-entry TRV, so that you can re-enter Canada again). It also depends as to how long you will be staying back in your native country and if you are staying any longer, then the particular course you mentioned at Algonquin of 1 year won't provide you with sufficient time ( just 1 year post grad work permit) and hence it will be very logical and highly reccomended to do a 2years PG cert/diploma course at any college and gain a 3 years post grad work permit which will not only give you enough time in hand to do your stuff, but also (if I get the question correctly) let you stay more than 2 years (3 years in this case) after the completion of your course and hence giving you all the time in the world.
Getting admission to COLLEGES has nothing to do with your cgpa/marks (unless otherwise stated specifically for a particular programme which is rare), and all you need is a Bachelor's degree and a good IELTS score (usually minimum 6.5 overall).
If you really want time in your hand and want to stay in the Ottawa area too, you will have to search for a 2 years post graduate course in a college (related to your field, which I assume is Business) and which I think there is none in Ottawa (again you will ahve to do research) or go for a 1 year post graduate course, which will keep ur time very limited.
And, my dear obviously, you are not the 1st student who doesn't want to go back from Canada to his/her native country after studies!
you don't need to mention that, unless the opposite is your motive!
Conclusion: If you are unsure about tour schedules, and want better shots at getting that coveted PR, its logical to opt for a 2 years PG cert/diploma course and get a 3 years PGWP.
Hope, it clears your queries.
Best of luck
tiger007