Can I got my iPhone replaced and when can I get my new one?

Hi guys, I got some questions with my phone and am appreciated that you can answer me.

I bought my 16GB iPhone 4 a year ago and it was out of warranty after February. Originally it was locked to fido (the Canadian carrier), but it was factory unlocked later. Before that there was a problem with this phone, when I made/ received phone calls from the others, the other party cannot hear me at all, or it worked for about 5-10 secends and it went down again. I checked the forums and found that it was a hardware problem. And I know there is a OOW service that allows me to pay $169 Canadian dollars for a new one.

And here are something I want to know:

Can I get the replacement for that?

Which version do I get for that (16GB or 8GB or the upgrade 4S)?

Do I get the unlocked one?

How long does it take to get my new phone? (As I live in a small city and there is no Apple Retail Stores here. To get the replacement I need to go to a larger city like Toronto or London, so I want to know if I can get a new one on the same day in store.)