The normal number: players plus one. The Advanced variant only changes the opening deal (5 cards, keep 3); the discarded cards are shuffled back into the deck before play. Some translated rulebooks omit the "plus one", but the publisher confirmed no change.
Players report that it works fine: waits for draft picks are a little longer and the draft is less cut-throat. This is player experience only, not a ruling.
Yes. Look at them as soon as they are dealt, keeping them hidden from opponents. You still pick your Region card first and then choose and play one Sanctuary. Revealing your choice before the Region card is also allowed.
Deal and resolve one player at a time, in the same turn order used for claiming Region cards, instead of dealing to everyone at once. The publisher gives this as the official procedure. Late in a large game, with many Sanctuaries already in play areas, the deck can be too small to deal to everyone at once.
No. Choose one to add to your play area and put all the others under the Sanctuary deck. Some French printings were ambiguous; the publisher said that was fixed after the first print run.
Score each Region card once, from the last card you played back to the first, then your Sanctuaries. Flipping the Region cards face down first, as the rulebook says, makes it easy to reveal them one by one.
The publisher said it would work just fine that way too, but the rulebook scores right to left (retracing the journey), so that is the standard way to play.
The tied player holding the single lowest exploration card wins. Compare only the lowest card, not the total of the durations. A thread disputes this, but the publisher answered it.
Mystical Havens are the grey cards, new in the expansion. Some of the new Region cards and Sanctuaries score for grey cards. In the base game grey is colourless.
The cards are correct. The publisher confirmed the printed Region card and the matching Sanctuaries are right, and the rulebook figure is only an example to illustrate the rule.
Every card in your tableau whose exploration duration ends in that digit stays face up, including earlier ones. The Meteorite card itself stays face up even if nothing matches.