I obviously haven't thought about this as long as you have, but offhand I think that model is a mistake. Only a small subset of people (and perhaps a bunch of companies) want things like proxy support or VPNs or other extra services. Most people just want to browse the web, so you're limiting your market a lot.
(I do think you could make value-added browser services a business, but you'd have to go to enterprises to do it.)
I don't see why. Passive income vs profit is not really dichotomy; passive income is a question of how much work you put in, whereas profit is how much you make relative to how much you put in. Regardless of how you structure your commitments, more profit is better than less profit.
You could argue that to be successful at generating a passive income of any magnitude, you'd be better off selling value-added services on top of a free browser rather than just selling a browser. I'd be curious to hear that argument, because the opposite seems true: making freemium work means that you need to invest not just in making a great free product that people will use, but also invest in creating enough additional value to make the sale. Thus I think wanting a lower commitment to the company actually says you should just sell the browser.
(I do think you could make value-added browser services a business, but you'd have to go to enterprises to do it.)