You can bring your wife and kids if you are in skilled or semi skilled category. Check NOC job classification. Wife- Open working permit. KIDS- student permit..
If you do satisfy the "highly skilled category" which lists NOC 0, A or B i believe, so yours is included.
There is no time limit, you could have even applied for wife and kids ALONG with your work permit application.
Spouse of temp foreign workers do qualify for an "open work permit" i.e. they can work for any employer. Main concern is the primary applicant. However, spouse or kids - both are considered in pretty much similar way any other applicant for visa is considered i.e. they will undergo medical etc. and would require all forms similar to the primary applicant.
Of course, if applying for an open work permit for spouse, you won't have a job offer for her and LMO, so you would leave those sections of forms writing "Not Applicable"
