If I am understanding this correctly, when using hordes for combat the following happen:

In Melee: If the entire squad is swarmed by 30 Cultists, each with 2 hand weapons, swift attack; the Horde will make 2 attacks on each of the 5 members squad. If the hordes hit any members of the squad, then the squad will take the damage of the weapon + 2d10 extra damage per hit?

At Range: If the entire squad is shot at by 30 Cultists, each with autoguns; the Horde will make 1 attack on each of the 5 members squad. If the hordes hit any members of the squad, then the squad will take the damage of the weapon + 2d10 extra damage per hit?

Sorry for the basic question. The Horde system is a bit confusing for me regarding attacks on the squad. Its either everyone is hit or one poor soul is hit. Thanks in advance for help and clarification.

In Melee: If the entire squad is swarmed by 30 Cultists, each with 2 hand weapons, swift attack; the Horde will make 2 attacks on each of the 5 members squad. If the hordes hit any members of the squad, then the squad will take the damage of the weapon + 2d10 extra damage per hit?

Almost correct, if the horde got the two weapon wielder talent(or multiple arms trait) they can make a multiple attack action with 2 attacks for swift attack and another attack with the second hand(more info on two weapon fighting on page 246 core). Also I'm not sure what you mean by the squad will take damage. The marine who got hit will take damage.

At Range: If the entire squad is shot at by 30 Cultists, each with autoguns; the Horde will make 1 attack on each of the 5 members squad. If the hordes hit any members of the squad, then the squad will take the damage of the weapon + 2d10 extra damage per hit?

Nope. The Horde will make 3 ranged attacks (30/10 -> 3 attacks) and the GM may decide which member of the squad those attacks hit.

The above is correct.

I'll add in the ranged example, the Horde makes 3 full ranged attacks INCLUDING any rules etc. associated with the weapons. Meaning the horde can make 3 FULL AUTO attacks, if their weapons can do so, when the horde chooses to use the FULL AUTO action. Each of the three (3) attacks benefits from the additional horde damage (in this case +2D10).

By squad I meant, I assumed the whole squad was hit, not just (1) player. That's rough, but I get it now.