So basically a MiFi, only with a blockchain integrated into it? And all of it is free (including the MiFi device itself and the annual subscription) as well as working worldwide? For example if I am an Hawaiian having a trip to Australia, my Xiden will still works perfectly?
No. Xiden is the blockchain. The Minter Guardian device, which is what generates the hotspot and validator pool, is not a free device. When you purchase this device, it comes with 1000 locked XDEN (the native asset of the Xiden blockchain). You start unlocking XDEN gradually by validating transactions with the Minter Guardian and any other devices you integrate in its validator pool (called the KrateR Pool) in order to boost its power. All those devices will be registered on the network and if you take one of those on your travels, as you mentioned in your example, it will automatically connect to any other Minter Guardian hotspot in its range, which includes internet access.
And your project (whichever the name you give for the internet service) is the one providing the connection? I mean, you provide both the device and the "mobile data" instead of providing only the device (minter guardian) which act as a MiFi and relies on existing ISP like T-Mobile or Sprint for the internet provider? If so, how do you enforce this global internet service? Because far as I know, even large companies like google with their Google Fi couldn't even reach the entire global-wide service yet.