I've also wondered about the protocols of accessing HQ, specifically how much information the Corp player has about the card(s) being accessed. If we go with the conventional way to do it, the Corp player holds his hand up, fans them out, and the Runner chooses one, looks at it, and does what needs to be done (steals, trashes, returns) with that card. Obviously, the Corp player will know what card is being accessed.
Alternatively, it could be done in such a way that the Corp doesn't know. For example, the cards in HQ are randomized, put on the table, and the Runner accesses a card. If he doesn't steal it or choose to trash it, the card goes back, and the Corp player doesn't necessarily know what information the Runner has about his hand.
As far as I can tell, the rules don't specify that the Corp should be in the dark about what's getting accessed, which they obviously are if it was a run on R&D instead. Given that the Corp can have knowledge of everything in the game, other than their opponent's hand and both player's decks, there's probably no reason to restrict their knowledge of what is accessed in an HQ run, but it obviously could make a difference.