On "Reducing your digital footprint"
It says a bunch of things I, and many others have a problem with.
I'll just respond to a few points:
1. Delete unused data - Actually the energy costs of you interacting with computers to find and delete data are almost certainly far greater then the cost of storing that data indefinitely, as long as it's not media (audio, picture, video) it's most likely very small. The major reason to consider deleting data is is it starts to become painful to find data, not (in general) the amount. At "large enterprise" scales the cost to store a terabyte, in a highly available fashion is now in the low hundreds of dollars a year, that involves having multiple copies available online at all times, and several copies in multiple locations on tape. When done in the form done by most web sites it's much less. Even if I include all my (archived) received e-mail my personal data from the last decade would easily fit on a DVD.
2. "save large files that only need to be read-only as PDFs" - This is actually a good thing to do, but for a different reason. Any file that's in a proprietary format (eg, all MS Office docs, even the newer docx/xlsx/etc. ones) may become unreadable at some point in the future if the software to read it becomes unavailable. Converting the data into a simple format (plain text, html, etc), or at least a (publicly) standardised format such as PDF helps prevent data loss.
3. "Delete accounts you no longer use" - worth doing to prevent issues when accounts and/or services get hijacked, but as mentioned above, the cost of the energy used to delete the data is probably higher then the cost to store indefinitely.
But there's other things not worth doing:
1. Unplugging "phantom loads". The vast majority of phantom loads really are trivial, and are not worth your time to unplug, this is getting even better as higher efficiency standards are being introduced. As a general rule if a (small) device is not noticeably warm to the touch when unused it's not consuming a large amount of power and you shouldn't bother unplugging it unless you won't be using it for weeks on end. Taking an occasional cool shower can save much more energy (especially if you use electric hot water)
Some things that might actually be worth doing:
1. Upgrade hardware every few years (and *properly* recycle old hardware). If you heavily use your computers and other devices the efficiency gains from new hardware can easily justify themselves, for businesses this is often *trivial* yet many companies don't consider this. At my previous job replacing all the servers with fewer, current generation, high performance servers would cut more then a third off a very expensive power bill, and mostly justified the equipment on that merit alone.
2. Fix teleworking. This more then most "digital" things is an issue, and one that the NBN won't solve, companies need to think about what roles remote, or even just occasionally remote, workers can take up. The fossil fuel saved from just a fraction of people commuting less often pays for the energy costs of one *very* large network. The NBN doesn't solve this because the majority of the problem isn't technical, but the policies and procedures at each individual company.