Hi Patrick,
Good luck. I've been doing app dev since Jan of this year. I blogged about the profits I experienced in the first few months here:
[http://burnsmod.com/business/2012/04/23/My-First-2-Months:-A...]
What you have right, in my opinion:
- you have low expectations to start
- you haven't quit your job
- none of your plans sound crazy
- of your proposed ideas, writing wordpress themes is probably the most potentially lucrative.
What you (may) have wrong:
- passive income in my experience (app development) is constant work. Whether its blogging to keep traffic up, answering customer support requests, to adding features or new revenue-generating products, etc.
- Blogging for ad revenue is not going to be very successful unless you start a porn blog. Blog for SEO gains and to funnel to your product sale pages.
- If you really want passive income, try to come up with something that is a subscription service people will pay you monthly for. It's a lot easier to maintain a service for existing customers than have to bring new customers in the door every month.