You can buy an iPhone 6S with monthly payments through Apple! You sign up for the
Apple Barclaycard financing plan. You will either be instantly approved or denied. As long as you are approved, you will be given a limit on the credit card. Then you may use it INSTANTLY online on Apple's website store and do either in-store pickup or mail delivery. (As long as you are approved, you have the new credit cards essentials logged into your Apple website store account.)
I did this with my MacBook. I only owed a minimum of $25 a month (minimum). Depending on what you amount of money you get loaded on the credit card, and how much you spend, it should be interest free for a select number of months.
I actually just paid mine off, before interest were to ever build up.
To answer your question on international shipping...I am not sure whether or not Apple's official website will do this.