Thanks for the screen.
The phone heats up when you're using data (not wifi) constantly, and with the screen on as well - so that's normal. It happened on EDGE as well.
So - if pings are really that slow, then either
- it's the area you're in (I see that the downstream isn't as fast as the upstream), or
- Zong's 3G isn't all that.
Would be great if other members (who have Zong) could show their speedtest on speedof.me as well. Btw, if you access the desktop version, you get a much more detailed graph (per test result). If you don't mind, can you do a test in the desktop version as well and screenshot that, please?