Upgrading

Getting a phone at a discounted price is only available every 2 years. You probably won't be eligible for a discounted phone until your current contract expires. You can pay full price for a phone anytime. Be advised, though, that if you are on the mobile share plan and getting the "out of contract" discount, you will lose that discount if you upgrade at the 2 year contract price. You keep the discount if you upgrade with Next or pay full price.

Not sure what you are asking.

If you want, you can pay full retail for a phone and switch it out as often as you like.
With Next, there are options to finance for 12,18 or 24 months. It depends on what payment plan you were put on when you purchased the phone.
The 2 year subsidized plans are different from Next and change your plan and pricing, you lose the line discount.