A:AnswerBoost is a MVNO and is CDMA. you might be able to flash it to boost with the apns but as it is designed for GSM the only definitive answer i can give you is no it will not work on Boost.
A:AnswerYes, it most certainly will. All you will need to do is set the correct APN in the mobile networks settings. An Unlocked S4 will be able to achieve 4G LTE speeds for T-Mobile and AT&T as well; and if I remember correctly, most (if not all) carriers in Canada as well.
A:AnswerYes, there are providers that support both 3G and 4G, but it depends on what service area they serve and what data speed is within the certain area.
Best Buy Mobile and Connectivity Specialist,
Kraig
A:Answer1. Yes, it is a quadcore Qualcomm CPU.
2. It will work worldwide. Data speed is subject to network.
3. It does come with a 1-year warranty through Samsung.
Best Buy Mobile and Connectivity Specialist,
Kraig