User preference to turn off Firefox starting with two tab

I've been all over the mozilla documentation trying to find out which command line arguments or userpreferences will prevent firefox from starting with two tabs open and also stop asking would I like to share usage statistics.

Here's a screenshot

What command line argument or user preference can I set to stop Firefox browser from starting like that when I provide the -new-instance flag?

For the startup pages, you might want to try setting startup.homepage_welcome_url.additional and startup.homepage_welcome_url.additional to about:blank.

The bar that asks to share usage statistics is called the "data choices infobar", and it's controlled by the preferences documented here.

You could programmatically "view" the data policy, by setting datareporting.policy.dataSubmissionPolicyNotifiedTime to something like 1483520304570 (the output of Date.now()) and datareporting.policy.dataSubmissionPolicyAcceptedVersion to 1. This will tell Firefox that you saw the bar. You could still disable data sharing using datareporting.healthreport.uploadEnabled, if interested.