Ok gang. I feel like a noob, but I want to clarify something. The mission Top Target that comes with Greedo, I'm confused about where the entrance is. Is it basically that once you deactivate the last of the 4 terminals, it becomes an escape tunnel at that spot? Or does the targeted hero have to return to the starting spot?

The blue rebel token is the "Entrance Token". The marked figure has to return to it.

Entrance and Escaping are both defined in the RRG.

Ok, let me ask a different question. Do mercenaries count as "Imperial Figures" for the purpose of this mission? That is, Imperial Figures cannot target the targeted hero if that character is adjacent to a healthy rebel, but is it only Imperial characters, or any unit on the Imperial player's team?

All figures controlled by the Imperial player are Imperials figures, regardless of they are imperial or scum faction

See Imperial Figures from RRG. All figures controlled by the imperial player during a campaign are imperial figures (spelled in full). Figures with the mercenary affiliation are also mercenary affiliation (mercenary symbol), and figures with imperial affiliation are imperial affiliation (imperial symbol).

Just to clarify a1bert:

When the word "Imperial" is spelled out in campaign, it refers to the side that is opposite the Rebel heroes, regardless of faction.

When this symbol is used, it refers specifically to units in the Imperial faction.

When this symbol is used, it refers to units specifically in the mercenary faction.

So, for instance, a mission might have a rule that refers to Imperial units. That rule applies technically to all units under the Imperial player's control. If it also had rules that applied to units of the Imperial or mercenary symbol, those rules would only apply to their respective factions.