Me & my boyfriend are planning to settle in Canada

Our current situation is that he's applying an MArch program from Dalhousie, British Columbia or Manitoba (it take 2 yrs to graduate except Dalhousie) then will try to get a full-time job to attain more points to apply the PR. Are we on the right way? Also plz could u help to provide the answers for:

Well yes you are but one thing that you need to know - since you mentioned he's your boyfriend and not husband or common law partner, then it would be difficult for you to be attached to his application for PR. You need to be either married or a common-law partner to be able to make your application attach to his. Otherwise it will be 2 separate applications and of course his will be stronger as he already would have graduated. Besides how are you going to join him while he's studying? Have you thought of that?

1) Is it hard to find a part-time job in Halifax, BC or Manitoba while studying and also for me, to get a full/part-time job? (we can do any basic jobs like cashier, receptionist)

I am only going to answer for Halifax.
Depends on what type of part-time job you are looking for. If you're thinking of office desk jobs yes its difficult. But if you're ok with McDonalds or Tim Hortons, you could probably find one but the other problem would where? If the place you work is so far out, than the travelling time from school and work would hurt your studies. Anyhow as long as speak good English and have thick skin (because you have to go around and ask, you can't expect to apply online and get people to call you),  you ought to be fine. Note: part time is 20/hr per week max and you have to apply for an off-campus work permit. However if you work for the university, then you need not have a off campus work permit. For the university, there's plenty of jobs you can do too e.g. night security being one of them and even on campus subway cashier etc.

2) how much do we need to bring except tuition fees to survive in those 3 places ? ( supposed we didn't get any part-time jobs may be upto 6 months)

Well, its hard to say, it depends on what kind of rental you pay and how often you travel. As a student you get a bus pass which means your public transportation is free. But the bus pass is only good from Fall to winter to early spring. Summer, is on you! Tickets per bus ride is 2.50 if I am not mistaken. Rental further away from the university is cheaper but makes for longer commute. The solution is - if you are both coming together and if you are married or have proof of common-law partner, then you can apply to live in Peter Green Hall http://petergreenhall.dal.ca
Reasonably cheap single or double room apartments for an affordable price. Its only for matured/married/common-law or family students! So once you graduate, you have about 2 mths to move out. I lived there for my first 4 and 1/2 years in Halifax. If you save and are prudent with your spending, you can make it 10000 for the first 6 mths. You see, 4500 is for rental (assuming you have about 750/mth) and, 150/mth for groceries (for us we supplemented with a  small plot of garden vegetables that we grow behind the building), 100 for phone and internet and misc for emergencies.

3) is there anyone who has studied at one of those universities? How was it life there? Any part-time job opportunities? Also can u share your job hunting experiences after graduation?

This makes for a long conversation. PM me separately and we can take it from there.