Being on a permanent resident visa entitles you to travel in and out of Canada/Australia for unlimited times. But do take note that your introductory PR visa is valid for a 5-year duration. Nevertheless, you are eligible to renew for this visa before its expiry date. Where you travel overseas and return to Canada/Australia after your permanent residency expired, you will need to obtain a five-year Resident Return Visa (RRV) to renew your permanent residence.
Once on PR status, you may choose any occupation that you are interested in and you are allowed to work with no restrictions. However, exceptions do apply for work types such as Public service or Armed forces. Only Canada/Australian citizens can apply for the jobs that fall under these two sectors.