[Endoperez]

RedRover said:
Query 1:
Is there a unit mod command that allows map movement but gives tactical battle immobility. A modding application would be a Siege Artillery unit (catapult, springal, trebuchet, etc.).

I haven't tested it, but #mapmove 1 and #ap 0 probably give this result. Catapults can be easily used as 60+ str units with Boulder as a weapon; Boulders have correct graphics, have range of (str/3) IIRC, and add Str to damage. Also, high str makes the unit better at breaking down castle walls.

Query 2:
When setting up a PD spellcaster (#defcom), is there any way to ensure the caster has gems without actually creating a scenario?
What is the effect of magic richness on PD casters?
Is there a richness setting at which you can be reasonably certain that PD spellcasters will have gems?

I don't think anything can make a province defense commander to have any gems at all, as they are always newly generated for every battle.

Query 3:
I am a little confused about the #castledef command in the Manual.

The Modding Manual definition gives this as a bonus in rebuilding defensive structures when besieged. However, the Unit Database defines an ability that is a Defence stat bonus when in a fort.

Are there actually two different effects, or is this a conflict in source documents? In other words, do the C’tis City Guards have the bonus defined in the current Modding Manual, or do they have some other ability that at present we do not have the ability to mod?

The ability is the same. Official documentation tells us why e.g. C'tis City Guards are better at defending forts, unofficial guides tell us what it does.

Guard(+X): The reverse of Berserk. If the unit is wounded and passes a morale check, the number is added to its Strength and Defense, and subtracted from its Attack. It will also never retreat from combat.
The application would be thematic: the Varangian Guards of Byzantium, the bodyguard of the King of Sparta (the 300), etc.

Again, I'm not sure if there would be need or use for a command like this... It's more of whom they are defending, rather than who the defenders are. Because of this, I offer my proposal as an alternative:

Mindbender (+X): The unit with this ability has an unnatural ability to control feelings of others, and mere glimpse of her eyes is powerful enough to bewitch any mortal men. The thought of him dying drives those near him into depression, and they are ready to give their own lives to protect the center of their lives.
Whenever a unit with Mindbender ability is wounded, on an area (spesific size depends on the ability's power level) close to him all friendly units that fail a [morale? magic resistance? both? either?] check become enraged, and become unable to feel their own pain as they try to keep the Mindbender alive. These units never retreat, can withstand more fatique (enc: - {X/} ) and their strikes become more powerful (+ X str). Any bodyguards attached to the mindbender unit are automatically in this state as long as the mindbender is alive.

Magic Path Switching Tool: This command would immediately follow a command for random magic path selection. It changes the random path to another path. Example:
#pathswitch 0 6
This example command would turn a Fire path result from the immediately preceding command to a Nature path result.

The application of this switch would be to mold random magic path results along specific lines—for example, allowing the Random Sorcery command to redirect, say, a random Blood magic result to another chance at Astral, or even a Random Elemental result.

I agree, this would be wonderful.
If random and preset magic paths aren't differentiated in the code, maybe some number code similar to terrain etc could be used to make it possible for a mage to receive a random magic from among chosen paths. This isn't needed if your idea works, and yours would be easier to use and understand, but other modding commands use format more akin to what I suggested.