For the tapes, just go everywhere and search (the magnifying glass button). I'm pretty sure I remember there being one in the cave, and there's one in Tracy's room in the office, but I don't recall where the others were. Though as I said, just visit every location and click the magnifying glass, you should have them all in like 5 minutes.
If you've gotten to the point with the tapes, do you have the ingredients Tracy asked for yet? Some of those are found by searching and at least one of them requires you to talk to somebody. Once you find them and take them to her you're on the course to the end of the game, or at least as far as it got. But it doesn't actually stop. She does a thing, and another person tells you she's going to do a thing, and then there's a message that you've progressed as far as it's possible to go, but you can still wander around and do stuff, there's just no more story that you haven't seen.
