First off, I'm using the original DOS version of the game, and a few bugs in my game I've noticed that don't seem to be addressed anywhere on the internet:

First, all the guides and websites I've found say that many Heroes have a certain number of "random" skills that they could come with when hired. However, whenever I play the game, these skills are not random. Every Hero has certain skills in every single game I've played. Reloading don't change the skills, creating a new game doesn't change the skills. Killing off the Hero and resurrecting doesn't change the skills. It's as if the game created the Heroes when installed and refuses to re-roll them.

Second, for some reason my Melee Heroes will occasionally do no damage when attacking. This isn't a case of them not penetrating the enemy defense. It's simply they do the attack animation, but no combat occurs at all (the counter attack also does zero damage). I know it cannot be a failure to penetrate defenses because a fully buffed Demi-God Mortu decked out with artifacts has 47 attack, and to think that he could repeatedly deal no damage to a 1 defense engineer is statistically asinine. I've never seen this when they counter attack, only when they initiate an attack themselves. At first I thought it was his Vampiric enchanted weapon and he was attacking at full health, but changing the weapon's enchantment has no effect on the occurrence of this.

And last, I seem to have somehow offset the game's hex data in one of my save games. I went from 500+ gold per turn to -32650 per turn in a negative way, and in a positive way I was rewarded with 16500 life books and 16500 nature books. Nothing I seem to do can change it back. Is this game lost or is there some way of recovering the save file? If it helps, the exact moment the glitch occurred was when I cast Black Channels on a champion Warlock unit that already had a shit tonne of other enchantments on it.

Final question, has anyone else ever encountered any of this, and are there any patches out there to fix these problems? None of the patch notes for patches I've found mention anything about these bugs.

edit: added patch question

Your saved game is corrupt and there isn't much that can be done about it.

If you're running the original DOS version, chances are it's a non-final one and thus very buggy. There might be an appropriate patch floating around somewhere, but since you're on GoG, the version sold here is the final one.

You are probably using an early version of the game, and may (in fact most likely do) have a corrupt save file. Possibly a corrupt install.

Heroes do have some random attributes, although they also (mostly) have some fixed attributes. These are set when you start the game. Nothing short of a restart should change the random choices, and nothing at all will change the fixed ones - obviously, that being the reason they are considered fixed.

The 1.30 patch is the final official patch, and while it still has glitches, the worst of the wackiness of earlier patches is mostly addressed. The game is mostly stable in patch 1.30. There are fan patches that address some of the additional bugs. However, no patch will fix a game save that has already been corrupted by bugs in the version you started playing it with. Corrupted saves are just dead, there is no solution except to start the game over.

Find Mystic X (champion level hero). If he's the same every time, then yeah, you're right. If he's not... there's one exception to your problem.