Yes, actually your hair will dread easier because the hair has been damaged, so it will hold knots a lot easier. You can use any method and the dreads will lock up.

These are the two things you should make your decision by

If the dreads get really long they can pull on the scalp if they get really long which can make you loose more hair.

Another way to look at it is that you will get to keep the hair longer, because the dreads will hold the hairs together.

It's really a give take situation, but I have never heard of anyone's hair follicles being damaged because of have dreads, it's just a warning that needs to thrown out there just in case anything did happen.

Do I have to stop conditioning my hair for a long time before I dread it?

I recommend not using conditioner for about a week before you dread, because it can make the dreading process easier.

Is there any way you put in temp dreads, just to see what they would look like?

You could use gel and put twist in your hair. Or you could add loomed dreads to your hair. Or make silky dreads.

Can I trim my dreads? How do I do it?

It's not really a good idea, because the dread will start to unravel because the hair that was holding the knots together before is gone. You will have to wait for the tip to lock up again and it's just a pain in the arse. But if you are going to do it the best way to cut it is like a flower, cut it at an angle and then put a rubber band around the tip and rub the tip against the palm of your hand everyday for about 2 days and then take the rubber band out.