Fido

If I got a new phone with Fido, can I still use my old Fido phone as well, by switching out the SIM card? Because sometimes I want to go hiking and play sports and I don't want to carry my brand new expensive phone, I'd rather use my old one instead....

I know there's a 15 day return policy from date of purchase, however my phone was delayed in being shipped for 2 weeks because it was back ordered. Does that mean I no longer am eligible to return or exchange my phone? I still want to keep my 2 year ...