Concerned about Data Usage (multi-tasking question)

Hi Guys,

I am completely 100% new to the iphone. I came from a windows mobile phone, so far I really love the phone.

Anyways just a couple of questions from a noob to the veterans of this site - not sure if you guys can even answer them since this is all semi new (multi-task stuff)

My concern isn't apps running on the taskbar using battery or anything like that, I have a pretty good grasp on how multi-tasking works with the iphone. My question is how do I know if an app is running in the background running up my data usage (I don't have the unlimited plan, currently on the 2gig).

I know most apps close when you click home key and won't use data. But what about a program like Meebo (it uses push I am still unsure about push, does this count as a text or is this all data usage?) Anyways having push enabled does it use a lot of data or not much? If I open googlemaps and click home key is it now disconnected from the net?

I read somewhere that it can still use the compass / gps feature, if I click the home key will the little arrow in the top corner stay if its using gps? (it always seems to close which makes me think gps is in fact off?)

Also is skype always running in the back using data??

I really like how apple did the task bar but my concern is for people on limited data plans, be nice to have some kind of a menu simular to the push one. Disable background data basically for certain apps.

 

Awesome thank you for the response I really appreciate it. I guess I am little worried because I used like 30mb today and I didn't even use any video / music streaming. But IMO its a new phone and of course I am playing with it non stop, give it a few days and I am sure my usage will go right back down.

Oh and so I know, Push notifications IE from facebook / meebo etc etc.. they don't use Texts at all? I have a limited text plan and don't want any surprises lol.