Hi Sir David and for all who have experienced my dilemma.

Three weeks ago I came to visit a family here in BC, I wanted to try working here
since I can stay here as a visitor for 6months max (if I'm not mistaken). I already searched that I'm eligible in applying the temporary permit, so how are they going to do this after I gave them my application are they going to verify all the details to the US embassy? Are they going to call my past employer?

I also read that some permits are issued upon entry, do I need to go back in the US and apply for it? Please help..

Without knowledge of the work you are pursuing in Canada, the details of your qualifications, and the category of your application, it is difficult tp provide useful information. In general: no, Canadian immigration officials would not typically contact a US embassy to verify any details; yes, cases can be processed at ports of entry in some cases for eligible candidates arriving from outside of the country.