Does rest time depend on type of exerc. or is it optimal to rest from 30-120 between sets?
No universal rules. If you are lifting primarily for strength (low-rep high-load), rest as long as needed to feel ready for the next set. But with a single work set, a minute or two should be plenty. For multiple work sets, you'll need more.
If you are lifting for conditioning, then shorter rest times are more appropriate, even as little as 30 seconds. But you have to be using weights that you can recover from in 30 seconds.
All of the elements, exercise selection, rep-set combination, rest times, and loading (weight lifted) all have to fit together in a way that makes sense. You can't expect to lift a 5RM set, then rest 30 seconds or even 2 minutes, and come back and do it again! On the other hand, you shouldn't do light, fast sets then sit around for 5 minutes between sets.
If you are really only doing a warm-up set then just 1 work set, the time between these shouldn't matter much, just load the bar and go. If the next exercise has some overlap with the previous one, you'll want to rest a bit before moving on to it.
In this, like in so much in resistance training, you can get information in print or on line, get ideas and opinions from friends in the gym or in forums (like us), but the deciding factor will be trying different things in real life. If you want precisely-timed rest times, pick a time, try it for a couple of workouts, then vary it. Try 30 seconds a couple of times. Then try 45 seconds. Then try a minute. See what happens. Are you able to complete the number of reps and sets that you want to complete (I'm assuming that you have good reasons for choosing the rep-set combination you are using)? Are you making progress?
For me, timing rest is annoying, and I can't ever remember to do it anyway. So I almost always go by feel.