Heroes of Might and Magic II Reference Guide, Heroes2Info, by Qwerty.

It would be possible to create two versions: one with images and a lite version without images, with and without links. :)
As I mentioned in a private message, it would be good to use PNG (or at least GIF) for the images, as Heroes 2 has a limited color palette, and there shouldn't be any color loss.

However, I still think the layout is a bit dry. For example, in the section showing the building table for different Castles, there should be images for each building and a separate image for the entire Castle. You could also add an image showing what the Castle looks like from above, but you already have something similar towards the end. :)
I would also add small images under the terrain types and secondary hero skills. I don't know, but for me, they make the reference guide more engaging. Of course, it's a lot of work. Besides, you've already done a great job, and the reference guide is interesting and useful, no doubt about it. :)
I don't think the images will significantly increase the PDF file size. But, as I said above, you could create two versions. :)

Your recommendations would also be helpful, as you have a lot of experience. You could write them at the end, but it should be mentioned that they are:

Currently, the reference guide lacks a subjective element. But if I start giving recommendations on building, upgrading, or combat (as I do in my articles), the objectivity will begin to blur. After all, these recommendations are far from indisputable, and their scope of application is limited. They are not universal recipes.