Stop Firefox starting with two tab open

Question

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?

[edit] I am on FreeBSD but linux instructions should be fine as well. I am running the latest version of Firefox, this image is firefox 50.1

I launch firefox like this after I first create "/path/to/profile/prefs.js"

firefox -marionette -profile "/path/to/profile" -new-instace

that profile only does a few things, basically sets up marionette

marionette_prefs_enabled = "user_pref(\"marionette.defaultPrefs.is_enabled\", true);\n"
marionette_prefs_port = "user_pref(\"marionette.defaultPrefs.port\", %d);\n"%(proc_port)
marionette_prefs_startup_page = "user_pref(\"browser.startup.page\", false);\n"
marionette_prefs_upload_enabled = "user_pref(\"datareporting.healthreport.uploadEnabled\", false);\n"
marionette_prefs_service_enabled = "user_pref(\"datareporting.healthreport.service.enabled\", false);\n"
marionette_prefs_service_first_run = "user_pref(\"datareporting.healthreport.service.firstRun\", false);\n"
marionette_prefs_service_first_run2 = "user_pref(\"toolkit.telemetry.reportingpolicy.firstRun\", false);\n"
profile_path = '-profile \"%s\"'%(path)

as you can see, i've tried to disable a bunch of those things from the documentation i've found on the mozilla site but they still do not work. Hence this question.