You cannot jailbreak an Android, jailbreaking is only for iDevices. You can do a similar process called "Rooting". This can be done with popular programs like KingoRoot and 1ClickRoot.
Yes, you can buy the Samsung Galaxy S4 directly from Samsung.
Yes, the Samsung Galaxy S4 is a smartphone.
Yes. They have the Samsung Galaxy S4 Active.
No, the Samsung Galaxy s4 is larger than the iPhone.
The Samsung Galaxy S4 was released on April 2013.
Yes, Amazon.co.uk does sell the Samsung Galaxy S4. They have a wide variety of Samsung Galaxy S4 models and accessories available for purchase directly through their website.
The Samsung Galaxy S4 mini is more popular than the S3 mini.
The Samsung Galaxy S4 accepts a micro-SIM, but not a nano-SIM.
You can't jailbreak it!
An unlocked Samsung Galaxy S4 is presently between $550-650 USD.
The Samsung Galaxy S4 is not waterproof. The Samsung Galaxy S4 Active however is water-resistant, meaning it can withstand water (and dust), but can only stay submerged for 30 minutes for one meter or shallower.
No. You don't need to jailbreak it.