I am a landed PR but do not have a PR card. Can I enter canada from US by road on COPR and submit my PR card application. Is there a limit on the number of times I can enter canada on COPR?
You cannot enter Canada from US using your COPR. You need a travel document to re-enter Canada. Visit your nearest Canadian Consulate to apply for one.
http://www.cic.gc.ca/english/information/applications/travel.asp