“By using a VPN, aren’t you essentially transferring your accountability to the VPN provider?”. This is true if you aren’t paying for your VPN in an anonimous way, which is why 99% of the “VPN fOr PRiVacY” are scams.

tor is an onion proxy software, and tor-browser is a custom version of firefox which uses tor to connect to the web. Usually when people say tor they mean the tor browser but you can actually have any browser use tor (although it’s less safe). You should look into something that can control a headless browser like puppeteer and have the headless browser use the tor SOCKS interface. I don’t actually know if that’s possible, never tried that, but I think that’s where you should be looking.

what you are saying is plain wrong or not explained well. Using tor with javascript enabled you are getting the javascript anonymously, however in the process of running that javascript there is a risk of deanonymisation (for instance, that javascript code could be doing fingerprinting and other bad stuff).