It's a way of sending SMS messages from your computer/browser via your phone. Install app on phone and access the service via the MightyText website.
So far it works great. No need to touch the phone when you're at your computer if you want to send or reply to messages.
Other similar things I've used in the past either didn't work with certain internet connections, didn't update quick enough or didn't seem to always have the SMS messages in your current conversation on your phone.
He'll be in Wales. Close enough to England that he's able to use an extension cord to get electricity, but far enough over the border to be untouchable should the Feds come knocking - they have no concept of Wales, it's just no on their radar.
Ever heard of any criminal kingpin hunkering down and lying low in Wales? No, 'cos they're all keeping it a secret. It's the perfect haven for them.