If I have facebook on my phone and dont log out of it and just shut the app down does this carry on using my data? Also if I go into the settings and then applications to look at the running applications can I shut any of these down or if I left them open would they use the data, I do deactivate the data network whilst in work and at night when the phone isnt being used so will this save my data? Sorry for all the questions, only just started using this phone and have been used to the Iphone. Also what do the green and red up and down arrows mean that flash on an off at the top of the screen??