Looks like it is rendered to a page size that is intended to fit nicely on the device's screen at the default zoom/dpi settings without significant borders and have the text at a comfortably readable size. Look at the print preview in Adobe's reader with page scaling turned off and you'll see the difference. The other editions I've looked at would print nicely at A4 size, if this was printed like that the text would probably seem too large.
Yes. In fact, somebody from Apple contacted me about that. Won't be that soon though (especially, need to figure a way to integrate with the current subscribers database).
Why would this be tagged [scribd]? I always thought that "scribd" would denote a link to a scribd.com page with the document, but this is a direct link to a PDF.
No. The first few were and a couple of specials have been. but the rest are $3 in digital form.
All the content is originally sourced from HN (though some of it may have seen a little editing before being sent to print) and the sources are linked to from the HM contents pages. So for instance the page for last month's edition (which had no free variant at all) can be found at http://hackermonthly.com/issue-16.html, and each of the articles in the contents list is a link to the original HN post (and comments) which in turn links to the original content.
So you have a choice:
1. buy the print versions and have a nice printed magazine to read on the loo
2. buy the cheaper nicely (and relatively consistently) arranged digital version to read on your preferred device for that sort of thing, or print pages of yourself
3. just used the contents pages as a free curation service pointing you to some articles that are considered particularly good, which you can read as you like and print if you want to take a copy away from computing devices (though you may need to tweak the originals to print nicely, which is done for you if you buy either of the above)