If you get the crack from a reputable source, you can trust it will be safe. A low seed torrent from a shady place (like The Pirate Bay) is probably a virus. High seed torrent from another source like 1337x or something with more active moderation is generally safe.
If you want to be extra sure, spin up a VM and install the crack there and check it out before doing it on your real machine.
The onset is pretty fast because it’s going straight into your lungs and bloodstream. Within a minute of inhaling you’ll notice the feeling.
I would recommend talking to a dispensary about what you’re looking for. If that’s not available, try talking to your dealer or someone who knows more about smoking in your local area so you can get some reputable information.
Generally speaking, it sounds like a mid strain is what you’re looking for. Roll some .5g joints so you can smoke them in littler portions.