Your insurance company could do the hiring, taking care of it all, the only thing, is the check, the payment will be sent to the contractors by them. You will not see that check. (So, if you are trying to save money by hiring on your own sometimes, that is really a hard thing to do unless, you are really knowledgeable of trades.) But, your house will be taken care of, and if you trust your insurance company, and if you never did this before, in making large repairs, I think, it can be the easiest route for you to take. One additional thing, if something is not going right you can talk to the insurance company; and, they deal with the contractor and that, can be a blessing at times. It takes a lot off of your shoulders, and can give you peace of mind. They will be responsible for the repairs being done satisfactory.
So far as the updates, what caused the fire? The contractors, will tell you, what needs to be done. If any updates are to be made, unless, you were familiar with your home to that degree, you probably, wouldn't know the difference unless, it is big; and it will be better for you to have it done. It really is not a matter of choice for you. They have to do things to the codes, and to the terms/specs of your existing insurance policy, or your insurance policy may not be renewed.