If I receive an e-mail with the sender being in California, will the time stamp in the e-mail header be the time he/she sent in their time zone (Pacific) or mine (Eastern)?
The timestamps in email headers are UTC (if the client is following the RFC properly). In the standard display mode (not looking at the header in detail mode) will display the time in your timezone by converting the UTC timestamp in the header to the local timezone as defined on the viewing computer.
Yes of course. Right click on the senders name or email id and then after right click, click the item "inspect element" You will get all the details you require