Absolutely. You can see Mozilla attribution in the Google URLs. (Unless you've modified your search engines--which Mozilla has made harder to modify.)
They have indeed made it a lot harder to modify. And even harder to set it to Bing! Earlier it was just a dropdown in settings.
Uh, i thought it was easier? All the options for search engines are in the results in quantum
Because 99% of the population use Google so they make their browser do what the customer expects. Not everything is a conspiracy.
Because they know what their users wants?
Most people switching to Firefox are doing it because they want choice. I know that was my motivation. It's not an upgrade over chrome in any other metric.
Because its the only sensible search engine and setting it was default improves the user experience of firefox.