Hello,
Happy to try to help you get these things resolved. 
Let’s start with the Textbook field first:
If you don’t already have it installed, the AnKing Note Types add-on makes adjustments like this a lot easier so I would recommend using it (assuming you don’t already have it). The add-on page is here (https://ankiweb.net/shared/info/952691989) though if you’re familiar enough with installing an add-on the code is thus: 952691989
You can install the add-on within Anki by going to your top menu bar, clicking on Tools - Add-ons - Get Add-ons, and inserting this code. Once it’s installed you’ll want to restart Anki.
From there, once you’ve restarted Anki you should see ‘AnKing’ on your top menu bar, like so:
Clicking ‘AnKing Note Types’ should lead you to a screen like this:
Under the ‘Font’ tab there should be an option to ‘auto reveal’ individual fields in the note (I used a different field as an example here since I don’t have the Ankisthesia deck, or note type, installed, but the basic process should be the same) :
And then we can move on to the images themselves:
I haven’t used that deck personally so I’m not quite as intimately acquainted with it but a quick glance at the deck landing page seems to indicate that the textbook images are hosted separately:
If you click on the ‘View on Community’ link from that deck landing page, it appears that at least one person in the comments has linked to what looks like an externally-hosted media folder, which might do the trick:
[Wiki] Ankisthesia by Ankisthesia - #13 by anking.jacob…
Give those things a shot and let me know how you fare, and we’ll go from there. 