[enz]

1) 20h/week seems like a pretty big chunk of time. If you can allocate that much, it's a good thing. There are surely some great apps you can do with that time.

2) It depends. If your app consists in a simple "CRUD" app (most apps), you don't need fancy algorithms. However, it's always a good idea to know some fundamentals. You can learn that on the way, though.

> A feature like adding a new way of auth take at-least 2-3 weeks to complete at large enterprises with multiple folks working full time. What chance can an individual have against these large companies?

I don't think so. It can take 2-3 hours as well. It really depends on which company and what kind of software we are talking about.

3) Learn as you build it, it's much more fun and encouraging!

4-5) I think it's always valuable to spend time learning/experiencing in a new field.