I'm a portuguese citizen living in ontario canada and I'm in the process of booking a trip to the dominican republic for 7 days .my passport expired about 4 years ago and I just want to know if the procedures to renew would be the same or if things have changed with any new laws,also wondering if I should expect any problems leaving or re-entering into canada.

You will need a current passport, you should be able to get it renewed by contacting the local embassy

Contact Portuguese Embassy in Canada...

To renew passport has nothing to do with your legal status. You won't be asked.
If you have no legal status in Canada, you won't be able to return.