Reservist call up duty while in Common Law

Hi

We are in the process of applying 'Sponsor - Common Law' from my Canadian girlfriend. However, I would like to know if I am allowed to go out of country for my 'Reservist call up duty' in Singapore (which is compulsory since I do not have a Permanent Residence status nor a work permit. I've been looking for an employer in Canada since 2004. I have been in and out of Canada due to my Reservist/Call up duty from my country. I am drafted for military/police and I have been called again for 1 month every year. If my application of being 'Sponsored' go thru and I have to be with my common law for at least 1 year, How do I go about if I have to go back to my country and would these proved that I have been with my Common Law for that period of time?

I came from a country which doesn't require a Visitor visa or Temporaily Resident Visa to enter Canada.
My main question is, Is there a way where I can obtain a work permit while being sponsored during that period of time, hence, I don't have to be in and out of Canada. I have been thru to get information at CIC and I think my case is a little bit confusing the fact that I am not a PR in Canada even though 'If' I am being sponsored. CIC has no information about it and yes my involvment with my country has nothing to do with CIC.