Having finally (finally!) been able to get an expansion for the core set, I sat down and started going through all the shiny new rules. One that caught my attention, and immediately raised a question, was the integration of tier gear into the game. In the core set, during Rebel Upgrade phase, players peel off the top 6 cards of the tier in question, and can select any of those items to purchase. The rules state, when using one or more expansions: "Rebels no longer draw six cards from each item deck listed in the campaign log. Instead, players should make note of the total number of cards in each item deck at the start of the campaign. Then, during each Rebel Upgrade stage, Rebel players draw a number of cards from each of the appropriate Item decks equal to half that number (rounded up) for the respective deck."
Am I correct then, in assuming, if there are 24 cards in the Tier I pile (just picking a random number and tier), that the players would then draw 12 cards? If there were, say, 28, they would then draw 14?

Another question, if I may. At several points, the mission calls for a unique figure to be used. For this, we will use IG-88 as our example. Can IG-88 be used as an Open Deployment in missions where he is not 'starring'? Do I have to 'unlock' IG-88 through a mission before I can use him? I know that the expansion pack for IG-88 comes with a mission that would allow me to 'unlock' him for the Imperials. But what if one lacks that expansion pack?

Can units from expansions be used in different campaigns? Could I take the Riot Troopers from HotE and use them as Open Deployments in a core set campaign? Can I take units from the core set and use them in a HotE campaign as Open Deployments?

Generally, put new cards to their respective supplies. Yes, for items during upgrade stages you draw half of the starting number of cards from the respective decks specified.

All unique villains need to be earned to be able to add them to your open groups if another ability (e.g. Agenda card) doesn't specify otherwise. If you don't have the mission (and win it) to earn a villain, there is still a possibility to earn villains with the Nemeses class deck.

All deployment cards are added to the pool and are available in all campaigns. Note the Habitat restriction of some of the units though.

All heroes can be used in any campaign.