I’m a fan of the Zenhabits approach, myself. And I also have to be careful with not presenting myself with a huge task list, as it will lead to inevitable overwhelm. That was one of the primary things I spoke about in that guest post on the Producteev blog I mentioned.
Mostly, I focus on just adding in the most important next actions, though, on high priority days, I sometimes make a sub-list — or perhaps it is better called and over-arching list — of the major things that need to get done, just so I can have an at-a-glance look and re-look at them. This can be done in various way in Producteev, including priority starring, due today filters, and specialized labels, but I will often create a separate list — sometimes on (gasp!) actual paper — just to make sure that it is both in my face and hammered into my memory. It helps to keep me from allowing in distractions. Also, it is not common for this to happen in multiple contexts at one time, but when it does, having that external list to refer to can be a lifesaver.
Not the most purely GTD way to do things, but I am not in any way a purist. I use what works for me, and I recoomend everyone else do the same.
Stars, someday’s, and inactive tasks — It sounds like it works well for you so far. You might also want to consider a label in each context for “upcoming tasks,” or even a someday/maybe in each context, as it might add an additional layer of visual organization.
I’m curious about your Gcal problems. I use Gcal all the time with Producteev and have never had an issue. I would like better reminder or reminder/syncing options, and better recurring events connections, but other than that, no issues at all. There was a bug a while back that caused workspace calendars to act strangely or display weirdly in Gcal when workspaces that were connected to Gcal before there was a scheduled task in that workspace. I think that has been fixed, but am not sure, as I created dummy tasks as a workaround. If you are having an issue, their support team is very good and very hands on.
The Pomodoro system is definitely intriguing. I’ve actually tried something similar on my own, before ever hearing about Pomodoro, when I was working on about seven projects at one time. It’s an interesting balance between focus and multi-tasking, but it is really hard to stick with when you are a “project obsessive” — which I definitely am!