Is Firefox a trustworthy browser?
Firefox is considered a secure and private browser. By default, Firefox blocks known third party trackers, social media trackers, cryptomining scripts and fingerprinters from collecting your data.

Does Firefox use Google as a search engine?
Yes, Google pays hefty royalties to Mozilla/Firefox for making them the default search engine in Firefox. That deal is worth around $400 million per year (as of 2021-2022) and makes up the vast majority of Mozilla's total revenue.