Ok, well theres another APP available that seems quite popular in Thailand called LINE.
Download it for free from the Google playstore. Simply register on the app, and goto the setting and assign yourself a username.
Now when you want to talk to one of your new friends anywhere in the world, simply give them your LINE username and start sending free messages. Simple as shit!
Getting yourself credit for you phone is also a pretty simple process, you can pick up a pre-pay SIM from most 7-Elevens for the AIS network through 12CALL. Topping up is simple and sold in 100THB blocks. Make sure you use free WIFI though when available as using your credit can chew through it rather quickly.