Script to detect and record network statistics?

Script to detect and record network statistics?

I am new to scripting, I have a requirement to write scripts to be used on
my MacBook pro to record data usage on my broadband connection.
My Requirements
The script should detect Internet connection is via dongle or wifi
If via dongle then record number of bytes sent and received upon every
connection
It should log to a file at regular interval
If possible summarise total number of bytes sent and received may be once
in a day from 6 am to 6am. (it can also summarise upon next start of the
system ..next start of the system could be at 10am...but once summarised
should not be considered for next run)....Or Once a month
Able to figure out total bandwidth usage ....for a month...
My question is... On Mac...which script language would be better?...Apple
script's, or shell script or using python...etc...
If possible please provide pointers for the same. Thanks in Advance