No, but I have an iPhone 5 on Sprint's Everything Data 1500 family plan in Phoenix. (you can't get that plan anymore, it's discontinued).
They are generally crap at home and work. However, there are several places where it's pretty good. Just not many of them where I am at.
Sorry, can't speak to the iPhone for Life plan (get it with Easy Pay so you can own the device instead of leasing it). But yes, there is tax and fees.
International unlock requirements:
1. Service with Sprint for a minimum of 90 days.
2. Pay the bill on time each month.
Meet those requirements and Sprint will unlock the device for international use only. Sprint never unlocks for domestic use, although in February of 2015 they will be forced to start doing that for devices manufactured as of that date.