Arduino Mega an Wi Fi connection

I m developing a project with Arduino Mega for elder people. This is a carry on device, so the device will be moving in different wifi networks with obviously different ssid name and different password. The device will have a display and a query will be displayed requesting these two information. On this times any one can help with this configuration and the issue is not big deal. However as the data acquired by the device must be monitoring periodically with a system installed in a computer managed by relative of the person or a doctor (could be in a different city or country) we need to know how to connect by internet to the Arduino. No many people know how to get the dynamic IP assigned by internet to a device so we need to use a NAME instead an IP. Some questions pup up....

1.- What king of wifi device we need to connect to the Arduino Mega to support the programs, routines... whatever needed to fullfil the requirements 2.- Do I need to access or create a DNS server to be able to use a name instead an IP? If yes, how can I do this? 3.- How to setup the wifi device and how to setup the arduino?

Thank you in advance.

1) The easiest would be the Arduino WiFi Shield because it is supported by the built-in WiFi library and examples.

2) The WiFi network you connect to will provide access to a DNS server. You can then connect to your server by name.

3) Plug the WiFi shied onto the Arduino. User the examples under File->Examples->WiFi to learn how to locate local networks and connect to remote servers.