Is it reqired to spray with saline?

If your doctor advised you NOT to do something you should not do it.  You should be worried if you are not following instructions.  Follow your doctor's instructions.  If you have concerns, ask your doctor.

No, sprays are not required. Some doctors may recommend it and that is fine, but your doctor knows your case best and so their instructions are probably going to be what works best for you. Every doctor's set of instructions for what to do after transplant is a little different, don't worry too much about what others are doing.

The most important thing is to follow your doctor's instructions. Every hair transplant surgeon will have a slightly different post-operative regime. Some involve spraying the recipient zone and some don't. Those that advocate spraying use a variety of solutions, saline being one of them. Having trusted your doctor to do your surgery, you should trust that the post-operative instructions you have been given are appropriate.

This is not required and no studies have shown it to be better then just plain water.  The advantage of saline is if you are in a place with dirty water, the saline may be a little cleaner.  However, in most developed countries this is not an issue.

Good daily washing with shampoo and gentle finger massage works well to keep the crusts off. If this is started immediately after the hair transplant, there will be no crusting as shown in this picture of a patient 10 days after a hair transplant in the web reference below