You can install our site as a web app on your iOS device by utilizing the Add to Home Screen feature in Safari. Please see this thread for more details on this.
Note: This feature may not be available in some browsers.
I didn't do the lease (wasn't available when I purchased) but I did get the 36 month repurchase guarantee, which effectively converts the purchase into something similar to a lease in that I can walk away from it after 36 mos. (or sell it! - depending on how private party resale value is for MS in Aug 2016)