Five Leagues questions

Are the restrictions during character creation permanent for the whole game?

The restriction on the number of heroes and followers is only at creation. Once you play the game, you may end up with all followers, all heroes or anything in between.

The restriction on missile weapons is likewise only at creation (though some players stick to it as a house rule).

The warband maximum size you select IS a campaign restriction but only to the number of characters you can bring into a battle. If your warband size is 6, you can still have 9 people in the warband but only 6 of them can accompany you into a battle. 

Five Parsecs questions

What does "reroll a natural 1 once" mean for the Krag special ability (Freelancers handbook)

If the new roll is a 1 as well, it cannot be rerolled again. 

What happens when a Skulker rolls 2D6 Credits at character creation? (Freelancers handbook)

As written, they still receive the full payout (Some Skulkers do get fabulously wealthy, they are just not good with money in general). 

What happens if a world is double invaded? 

Through a series of pretty unfortunate events, it is possible for a world to get invaded twice in the same game turn. While I am tempted to say that the place just disintegrates into chaos as everyone fights everyone, randomly pick which enemy if you have to fight. For Unity to regain control of the world, roll on the galactic war progress table twice treating each enemy separately. If EITHER roll indicates the world is lost to Unity, human forces withdraw completely.

Do Savvy tests succeed on a 6 automatically?

No. If the target number is 7+ a character without a bonus can't succeed at all. 

Can I spend multiple Salvage units on ship repairs etc. in one turn?  (Freelancers handbook)

Yes.

Lore questions

5P: In the "Creature" Salvage event, Swift get a bonus to tame the animal. Why is this?

They have a latent psionic field that makes them seem slightly less threatening. 

5L: Do the Threats cooperate against us or do they fight?

They may ally temporarily, though they are as likely to oppose each other and probably skirmish with each other when you are not looking. Many of them have mutually opposing goals or would ally only for convenience.

5L:  What "traditional" fantasy peoples exist in the world of 5 Leagues?

Goblins (part of the fey realms), Halflings (we already know this), Dwarfs (will be the focus of expansion 2) for sure. 

Orcs don't exist. Lizard people are covered by the Oldest Kin. Elves (related to but distinct from the Fey) do exist somewhere.