Thanks for your comments!
1. Yes, the AI for creature movement gets a little overwhelmed when there are a lot of other creatures blocking their way. A bit of the problem is due to the turn order, I think. I'll take a look at it again when I have a chance.
2. Right - not knowing your Allies' HP (or any other character's HP) during combat is by design. There is a spell called "Reveal Others" (1st level for all three magic using castes) which, when cast, let's you cycle through all non-player characters and see their HP and current conditions. Of course, using up a turn to cast Reveal Others is usually risky. In caves, etc. it can be particularly useful though.
3. Great! I'm glad you like the mounts. As you found, they can be used to transport commodities from market to market (buy low, sell high) to make some money. Besides horses, there are several other creatures that can be mounted. Enemies are sometimes mounted as well. It is possible to, for example, kill the character riding a creature, then use a Charm spell to make the creature an ally, then ride it yourself.
Another thing you might find interesting (but you might already know about):
Teleportation spells - it is possible to teleport into other characters to kill them. The character with higher HP will survive and have their HP reduced by the HP of the other character. Using the "Teleport Other" spell, one can teleport enemies into walls or other enemies to kill them. The "Teleport Party" spell lets you quickly move across the map.
Ships - it is possible to board a ship and travel by water.
And, not to spoil things too much, but later in the game, some rather advanced technology may become available for your characters to use.
Thanks again for making those videos on your YouTube channel!