You shouldn't pay the civil demand fee. You shouldn't pay anything unless a judge orders you to pay it. The store could theoretically come after you in civil court if you don't pay their civil demand, but I have never seen that happen. If you have already paid it, you just wasted some money.
As far as your criminal case, if you're a first-time offender, you will likely be given diversion or a theft awareness class or both. Once you complete the program, the offense will be automatically removed from your record and you won't have to tell anyone you were even arrested.
If you aren't a first-time offender, then you may have to do some jail time or pay a large fine. You should have an attorney help you. Having a theft on your record can make it hard to get a job. It may also have immigration consequences if you are moving to another country. Canada may not admit you if you have a criminal record.
You should probably talk to a local criminal defense attorney and an immigration attorney. Good luck!
Depending on the value of the items you were accused of stealing, and some other factors, your attorney may be able to obtain a plea offer of an "Infraction" for you instead of a Misdemeanor. If you obtain an offer of an infraction, you would just have to pay a fine to the court, and you would not be required to do community service, and you would not be on court probation for any time period.
While an infraction might be a positive result in this case, your attorney will still want to explore diversion/dismissal opportunities. And your attorney will review with you any legal defenses you may have.
You should consult an immigration attorney regarding the affect of a potential conviction of petty theft as a misdemeanor or infraction on your goals of residing in/working in Canada.
As the other attorneys have stated I would talk with a few immigration attorneys before you accept any offer. Canada is very strict on certain convictions. I have had clients who's only conviction was a DUI get hassled when they go to Canada. Some have even been denied entry.
Like I said when we spoke, your criminal case in the US can be easily resolved. What complicates your case is the immigration issue. If I can give you further advice please dont hesitate to call me again.