How to efficiently get multiple outputs for a given set of inputs?
Your answer to this question will depend somewhat on your long term goals.  Everything you mention: talks, journal articles, blog posts, tutorials, magazine articles, etc. can be worthwhile in the right circumstances.  Most of what you describe consists of taking variations on the same theme to different audiences.

In what circles do you most want to be known?  More generally, how will you measure success?  Say for example that your primary goal is to get tenure.  If you're at a high research school, then publishing an expository article for undergraduates may well be viewed (by your tenure committee) as a waste of your time.  In contrast, if you're at a liberal arts school, this may be considered just as valuable as getting a research article in a top journal.

You asked about incorporating this into project planning.  I suggest that you decide which audiences you are most excited to reach.  This will likely be largely independent of the particular project.  Then as you start on each project, think about how you can tailor your message to suit each of these audiences.  You may be surprised by how often you find you have something valuable to say to each of your target groups.