Old rules ----> New rules
PGWP
90 days ------> 180 days
Study permit extension
90 days ------> No change, still 90 days
LIMA
Has to be done before the work permit application. LIMA is not a visa or a permit. You need to get a LMIA to apply for a closed ( regular ) work permit.
Closed work permit
You need to have a valid study permit, no grace period is give.