You won't be able to receive sns if your account is in season hold. 

For the plan, it depends on your Tab situation. If you don't have any tab, then you could switch to one of starter plan by a rep.  But if you still have Tab on your account, then the cheapest plan I see right now is $32/mo or $45/mo depends on your Tab size .. and if you have some promo plan, you won't be able to get it when you come back.

How long you will be away? 

Thank you Mayumi. I do not have a tab and will be away until April. What is the best way to contact a rep to get a new plan from outside Canada? Thank you!

You should be able to pick a new plan from self serve. If that falls for some reason, the best way to contact them from abroad is through Facebook or Twitter DM.

I would ask a rep ( through FB or Twitter as Sophia mentioned) to put your plan on one of starter plan since you don't have a tab. This way you can receive texts when you need it. 

But, roaming can be add up quickly. You can turn off data and data roaming off in your phone if you don't want any accidental roaming.  Or removing SIM from your phone would be option too.  You can still connect to WIFI if it available.