🚀 go-pugleaf

Lot's of questions, I'll try and clear a few up for you.

      Can I make a form in .pdf that allows the user to enter details into it
      right there on the computer?




Yes. Acrobat comes with form field tools. You need to add the fields first before Reader users can fill them in.

      Point is it looks like Reader 8, at least, does allow editing, some at
      least.




Well some. It allows filling in forms as long as the creator of the PDF has added those form fields I mentioned. Also, the creators can enable a typewriter tool that Reader users can use to add text (but not change existing text).

      I took a look on the web and read some wikipedia article that made it
      seem like Adobe has buggered around with Acrobat and Reader in various
      incarnations in their pursuit of maximising profits and perhaps once it
      didn't edit and once it did and then again didn't... maybe like that?




Sounds like someone has been doing some "creative writing" on Wikipedia. Reader has always been a reader and Acrobat has always been the tool used to create the PDF's that you can view in Reader.

      A pdf is simply a graphic, isn't it?




It can be yes. But it can also contain live text and independent images. It all depends on how it was created to begin with.

Just keep in mind that Reader has always been intended mostly just for viewing and printing existing PDF's. The have added a few bells and whistles over the years but it's "mostly" the same as it has always been.