Specific question: Does Advanced Beta Test put trashed cards into the Archives faceup or facedown? As the card tells the Corp to look but not reveal, I currently interpret it as facedown. However, I'd like to hear what others think or how others interpret this, especially as far as official rulings are concerned.

On a bigger note, I think it should be suggested to FFG that they clarify exactly what situations cause a card to enter the Archives faceup or facedown. On page 13, the rulebook says that trashed rezzed cards go in faceup while unrezzed ones go facedown. However, special scenarios- such as that created by ABT- are a little ambiguous.

I think your first question can be answered by refering to the second.

Cards go to archives face down if trashed when inactive and face up if active.

Thus Acelerated Beta Test lets you trash the cards FACE DOWN as they were inactive in R&D.

I think that is somewhere in the rules or FAQ but don't let me search for it …

 General rule of thumb: if the Runner is looking at a card when it's trashed, it's faceup.  Otherwise it's facedown.

No clarification is needed from FFG. It is already very clear in the rules.

Trashed cards go to Archives faceup if they are rezzed, and facedown if they are unrezzed.

 I'm sorry about that. It's just that the mentioned rule (from page 13) was about trashing installed cards. I wasn't sure if it applied to ABT's looked-at cards as well because they were never installed to begin with.

Ser Folly said:

 I think that it's supposed to be based on whether or not both players have seen the card. At least, that's how we've been doing it. 

I.E. a card that is kicked by Noise's ability is put into Archives face down, because the Runner has not seen the card, but the Corp can when it enters the Archives. An unrezzed piece of ice killed by Forged Activation Orders hits face down because the runner still hasn't seen it, but cards trashed through Trash Cost or Demolition Run always go face up because the Runner has seen them. 

In the case of Advanced Beta Test, the Runner hasn't seen it, so it's face down. Honestly, if you trash an Agenda, would you want that sitting on top of your discard pile in plain view?