No. These are an optional DM's discretion rules item and thus are not used in the Ashes of Athas Campaign.

It does. You can choose a shield along with your armor if you wish during character creation.

Yes. These rules are standard unless over-ridden on the adventure level (specific trumps generic).

Yes. Instead of taking a ranged weapon or thrown weapon you may choose a second melee weapon.

Yes. They are listed in PHB 3 which is an approved campaign source.

Yes. 25 gp. Don't spend it all in one place.

Yes. The essentials line is an approved source for the campaign.