I've got 3 questions:

1) I can't find Devil's Caverns. Where are they located? (Turns out it was connected to my 3-rd question.)

2) I got confession from Yuliette and Truncquillus's letters, but I still can not accuse him. The only available dialogue option is to ask about Bishop's murder. (Solved)

3) Where is Guss's Ring? (Found it on the ground in Wastelands)

Well budy i'm stuck at the end too so i put this here

Where do i find the chain for commander pasque?
And i almost finished all the quests for act 2 but i really don't know how to incriminate Truncquillius and the duches.
I don't find any letters from that Truncquillius,i'm really stuck here.=(

vazhatavberidze
Thanks, figured it out. It turns out I was stuck just because i missed Guss's ring that dropped from a rouge.

Dragonul09
Chain is in Glatzburg execution place (go right from where you enter it).
To incriminate duchess, you need 3 proofs (Gravedigger's testimony, a shred of Cloak and Raimond's confession); That would lead to incriminating Truncquillius.

Thank you very much my russian friend.

im stuck at the colloseum . i cant find a key to go to lower levels .

Where can I find Truncquillius after the Judge allows to arrest him?

edit: here
http://www.gog.com/en/forum/inquisitor/cant_find_cardinal_truncquillius_after_i_gather_evidence_to_arrest_him
they say to look in the basement, but I cannot open one of the doors.

I killed him, but now I can't advance. He didn't get surrender, he just died. What do I do now?