You can ping a device. A device can't be ping. The ping is just done to see if you have a connection.
You need to send commands via ethernet, likely TCP/IP connections. You'll need to know what those messages are. Once you figure that out, question two is trivial. Just use the "write to measurement file" express VI.
You need to read the communication manual for the device to see what command or commands you need to send, and how to parse the data out of any response it sends back.
Then you can write that to the Write to Measurement file within the same loop if you have enough time, or sent to a separate loop through queues in a producer/consumer architecture if you don't want the file writes to slow down the communication with the instrument.
For instrument control, you have the option of using an existing instrument driver by simply using the Help> Find Instrument Driver option. At http://www.ni.com/downloads/instrument-drivers/ you will find links on basics of instrument control, what a driver is, how to use one, how to create your own, etc. Before you start messing with any code, you need to be familiar with the instrument and how to operate it manually.
