What's the best way to upgrade to the iphone 6s?

Right now, i have an at&t iphne 5s, and i'm upgrade eligible on October 4th. But i wan to get the iphone 6s 64gb, and i was wondering what would be the best way to buy? The att next plan, or the apple upgrade plan directly through apple?

Can I Preorder The IPhone 6S Without it interrupting my current contract?

I really want to Buy the New IPhone 6S but I don't know if I can? I got this message when I was doing it and I don't know what I Should Do. I Don't wanna cancel my current contract because it's almost over but my phone is broken right now. Here is the message I got: You can purchase a new iPhone. But the remaining contract commitment you have with AT&T still stands.
Your AT&T contract ends on December 18, 2015.
You'll need to select a new AT&T rate plan before you complete your purchase.

Does that mean I will have to purchase a new two year agreement even if I pay full price for it?

How much does the rose gold iPhone 6s cost?

I don't think the iPhone 6s is even out yet but I'm just wondering what the cost of it will be. I wanna get it with a plan though. So how much is it if i get the phone with a plan (after my contact with my current phone is over)? Does anyone know?

Will the iPhone 5c 8gb be enough for what I want to download?

I'm planning on buying an iPhone 5c 8gb because its the only GB I can really afford. I've written down all the apps I wanted and right now I have 12 apps. I'm not gonna be downloading any music because I'm gonna download soundcloud for that. I don't know how many pictures are gonna be on it tho. I still do have my old phone that I have some of the apps that I want to download on my iPhone on here, I wanted to limit the apps because I've heard lots of people say the 8gb isn't enough. Someone please help!

Apple iPhone 5 to iPhone 5s?

Okay… So. I heard that if you have an iPhone 5 still under warrantee, you can take it to an Apple Store later this year and get it changed to a 5s with no charge. Is this true?