Can you tell if your phone has been wiped via Find My iPhone? I lost my phone 5/think it was stolen. 

I had "Find My iPhone" on it. The thing is it was very low on battery and by the time I realised it was gone I think the battery was done - it just showed "device offline". 

So my question is, if somebody has taken the phone and has wiped it and is using it instead, would the Find My Iphone screen show anything different? Would there be some way to know that it can't be found again, or will I still be notified when they connect it to iTunes?
With Find My iPhone activated this disables an activation when the phone is wiped from a different computer. The person would have to know your AppleID and password in order for the phone to be activated again (meaning use a SIM card and get reception). If they erase it, you should still be able to see the phone on your map. I would recommend not wiping the phone rather track it. 

The commands become active the next time the device is powered on and gets a connection either via open WiFi or cell tower.

You won't get much in the way of information in regards to what they are doing with it. Tracking really is your best bet since it records the routes and allows you to follow the device, wiping it could make it easier for them to break into the phone and use it without your permission.