-your guess is as good as mine. try asking them.
-maybe. maybe not. try asking them.
-on the actual device the sender is definitely listed. it might be a short 4 digit number if its not coming from a cell.
if you receive a bill that only shows data, minute and text usage without seeing dialed/received call numbers and sent/received text numbers then it is most likely due to the company trying to save paper. i have verizon and they do something similar. for us there is an option (extra like.... $5/mo) to get the entire complete listing on each bill. perhaps there is a similar option for you.