I'm not a Skype expert but I imagine the strategy for using Skype (especially while overseas) would be to have callers email or text you to let you know they want to talk. Pre-arrange a time to be on Skype at a Wifi hotspot. Then boot up the app and make the call. Use computers on both ends if possible (then it's totally free except for any hotspot fees).
Skype will not make a voice call over 3G. You can only use text chat. You have to be on wifi to make a call.
Skype will not make a voice call over 3G. You can only use text chat. You have to be on wifi to make a call.