[AT&T Samsung Galaxy Note 4] aturyan:
Ok everyone, I think this might clear up some issues.

I talked with a T-Mobile representative and asked him thoroughly about how I can go about trying T-Mobile's service with the Note 4 and how I can cancel the service yet still keep the phone, I also ended up purchasing the phone through the phone with him as well after my questions were answered.

So here it is:

He said that I could cancel the service and return the phone within 20 days and would not be charged any fee at all. I also asked him how I could keep the phone and just cancel the service so that I could use it on some prepaid service. He clarified repeatedly that to keep the phone and just cancel the service, I would need to go to a T-Mobile Store and cancel the service through them, then I would be asked to return the device, or if I want to keep it, I could pay the store the remaining balance of the phone. You'll see it below but because I paid a down payment of $72, I would need to pay the remaining balance of $677.76. And that's it :D

Questions regarding unlocking and using on other carriers:

He told me he asked his supervisor about something like this today and he said that to use a phone on another carrier, you need to wait 45 days to unlock it. He thought phones already came unlocked but he asked his supervisor and it is confirmed to be 45 days.

There's already been talk about this in this thread, but if you wanted to unlock it before 45 days, which you would need anyways if you want to cancel the service, just keep the phone(and use on ATT), once you receive the phone, insert the sim and activate the phone to region unlock the device. Next, companies like CellUnlocker.net should have unlock codes soon once the phone is released.

And here's how my order process went and the breakdown:

First, since the Note 4 is a month-to-month payment phone, you need to sign up for service to purchase the phone.

When signing up, you will be asked to submit personal information like a Driver's License Number so that they can check your credit. After they check your credit, you will be told what your options are as far as financing and down payments.

According to my credit, which they said was very good, I did not need to pay an activation fee, just an initial $72 downpayment, $10 for the Sim Starter kit(which is always required), and sales tax. So up front, I needed to pay $150. To clarify, the $72 down payment is not an additional fee, it is an initial payment of the total price of the phone($749.76). So because I had to pay $72 downpayment, my monthly equipment installment plan turned out to be $28.24/month. If you do the math: $28.24 x 24months = $677.76 and add $72, you have $749.76.

Next, they asked me about what service plan I wanted to get. I chose $10 3GB of data and the $50 Simple Choice Plan with unlim. talk and text, so $60/month service.

So monthly, I would be paying $88.24/month if I were to keep the T-Mobile Service.

$88.24 = $28.24 Equipment Installment Plan + $60/month service

So there you have it, hope this clears things up. I actually plan to test drive T-Mobile for a few days and actually see how their service is before canceling.