How do i...

This is a list of what, at some point to you, will be "obvious" details about the website, but which you may waste time trying to derive when you first arrive.

Find what code runs what page on the site
First, try tools/ <route>. This should tell you what you need to know.

If that doesn't work, for most cases you can look at <site root>/ and, as of the time of this writing, starting at line ~375, are all the webapp2 routes for the whole of the website.

Find the main site template
for now, this is page_template.html in the templates folder, almost all html files inherit from it.

Re-Publish locally without finding some /devadmin url
curl "http://localhost:8080/api/v1/dev/initialize_datastore/publish"

Add a template variable that shows up on every page (i.e. for gandalf tests or what have you)
in, look at add_global_template_values you'll want to probably add an entry to template_values[].

Add a new topic badge
Assuming you've checked out the badge repo, you now need to update badges/ to include the new topic and also to bump the version number (?8) of the icons' urls.