Everything about heroes.

I strongly disagree here. As long as the experience required for the next level is measured in thousands (1000-20000), this "small amount" will be very useful. And this lasts up to level 25.

Of course, there are options. At the beginning, you can eat a few chests for experience and gold (which is understandable). But from my gaming experience, I can say: you can never have too much gold. I am constantly short on it. You will gain experience anyway in battles, just a little later than if you take it from all the chests. It makes sense to take chests for experience if:
1) you are just a little short of the next level, and that level is very important (for example, to make it easier to defeat strong guards, get the desired skill (offline), or reduce losses);
2) you are playing on a low difficulty level, and the map is rich in gold and resources, etc.

You should definitely take gold from chests that give 500 experience. I will say that a developed economy can do much more than your hero, who ate all the gold and gained 1-2 levels! Your opponent will build a level 6 dwelling, but you won't, he will be able to buy an upgrade, but you ate everything on experience, built something, and you don't have money for the upgrade, etc. I have never regretted taking gold from chests instead of experience.

For example, to go from level 16 to 17, you need to eat an average of 9 chests (let's say 9000 gold) or defeat 300+ guards. Usually, by level 15, 300+ guards do not pose any threat, but you can buy a lot of things for 9000 gold. It is especially useful to have extra gold if you find artifact merchants. Then, for that gold, I will buy more than your 1-2 primary skills on level-ups ;)

Moreover, I just don't like their "facelessness". I wonder why the developers didn't draw faces for them?

I didn't understand this.