Buzz Lightyear, I am so sorry you didn't get good news.
I can tell that you love him so very much. I wish my little Tipper had been well enough to have been groomed so she could cross as the beautiful girl she was. I think it is a good idea to have him looking his best if he is feeling well enough.
It is good that you can plan and prepare for what is to come. It will still hit you in the gut like someone punched you, but if you can plan and prepare, you can be in control. We were able to plan where we wanted to bury Tipper, get her an appropriate "casket" and have her special toys and blanket with her. I found comfort in this.
It will be hard for your family. Make sure your daughter understands as much as she is able. I don't know her age, but she will grieve and may not understand. One thing that really helped me was to write a letter to my little girl. I buried her with this. I just had to let her know how much she meant to me. If your daughter is really young, she might want to draw a picture. Make sure she understands that Buzz will always be in your hearts.
I'll keep your family and sweet Buzz in my thoughts and prayers. Remember, the most important thing is quality in life--not quantity. I hope your consult later today can give some encouragement.