[Nagot Gick Fel]

1) If some unit has more than one weapon, e.g. a lance, a mace and a hoof, does it use all of them in the same turn, that is, attacks three times?

Yes. Unless every available targets is eliminated before all attacks are "consumed", OFC.

And if so, is it the same thing as multiple attacks with the same weapon, that being - all of them are targeted at the same unit,

Actually it's "targeted at the same tile".

and that unit gets a -1 def with each subsequent attack? Or does the thing with -1 def only apply to attacks for various units, not multiple attacks from the same one?

Don't know.

And which weapon's length is taken into account for checking whether it can repell an attacker, only the longest one, or can it repell multiple times?

My guess is the longest weapon is always used, and it can repel multiple times.

2) What does the fear/awe morale check mean exactly? If a unit causes -4 fear, does that mean that the attacker makes a morale check with +4 bonus?

Nope, a unit causing -4 fear will rout enemies easier than an unit without a fear aura.

Why does the scale start with -4 anyway, instead of 0?

Actually it starts at -5 (causes lesser fear) or at 0 (causes fear), with +1 for each death/unholy level. I think it starts at -5 for historical reasons: the "causes lesser fear" ability appeared on death mages and unholy priests in a patch, while the "causes fear" ability existed since the initial release of Doms 1.

Do those failed morale checks just count as failed morale checks for the squad level, or can units that get frightened rout individually?

The former. Units (except leaders) never rout individually. A squad may rout after some of its units turned berserk, though, giving the illusion that its units display independent behaviour.

And how is morale check done in the first place (something with the dice, I assume, but the manual doesn't explain how)?

I'd like to know.

Is there a direct effect of fatigue on morale?

Possible, but I don't think so.

And, if I'm not mistaken, morale is not dynamically updated for each unit during the battle,

I think it is dynamically updated for each unit (or else the 'Frighten' spell would be irrelevant), but a squad's morale is checked only at the start of its own round, averaging the *current* morale of all its units. It appears to be a rather complex computation, as the squad's current size, and its casualty % both seem to count.

since it only matters for the morale checks, while the actual morale that causes rout is dependent on the number of units, not their respective morale, right?

Well, evidence says the "morale" of a squad is based on its size, and on the average morale of its units.