Short question - is active location considered in play? I just started playing black riders and i'm wondering if i can use ability of 3rd adventure card to place tokens on active location. Also, in order to win (in any other scenario) do i have to satisfy victory conditions + place tokens on adventure card only or do i have to clear active location as well?

And second one - do i have to do a hide test for a Black Rider revealed during setup? If the answer is yes, this quest is insane .

1) Active locations are in play.

2) If the Black Rider had been "revealed" during setup, the hide test would trigger. However, the card says to "Add" 1 Black Rider to the staging area. Cards that are added are not revealed, and the "when revealed" text is ignored.

Also, in order to win (in any other scenario) do i have to satisfy victory conditions + place tokens on adventure card only or do i have to clear active location as well?

Most of the time, it is just whatever victory conditions + the tokens on the adventure card. Some enemy cards will have conditions, such as you cannot win unless the card is in the Victory display.