Temporary cancellation and plan and number retention for 2 -3 months

You can go on seasonal hold plan. It's 15 dollars a month. You will continue to pay any tab you still have as per normal. You will have to pick a then current in market plan once you bring it back. If you are going to be gone for a few months, it could be worth it to port out to a VoIP service and port back once you're back. Then you still retain use of the number via data / WiFi use with the VoIP service and it'll cost less than doing the seasonal hold if you will be 2+ months.

Consider porting your current number permanently to VoIP. I give my contacts a VoIP number which can be forwarded automatically to any other phone in North America, not just Koodo. Current contacts never lose touch with you.

Phone rings home and away simultanously and I can make wifi calls without using any cell minutes.

Many VoIP services are free or just a few dollars a month, including call forwarding, but won't support text or picture messaging. Those have to be sent or received directly on your then-current cell number.

It depends on the VoIP.they usually charge a one time porting fee.Fongo is 25. I'm not sure about others but the price point on listed on their respective sites. Koodo won't charge to port in later. As I said, you must choose a new plan is you go on seasonal hold or leave Koodo.

But i am told that on seasonal hold, when you bring it back you have to choose a then available market plan and i will loose on the old plan. 

The only way to keep your current plan is to keep it 'live' during your absence.