After a 16 months of deliberation, I have decided to get 'Cuppy' neutered. I made the appointment about 15 minutes ago and they told me to bring him in tomorrow morning.

I didn't think it would be this soon. Now I'm freaking out not knowing what I am suppose to do. Do I take a bath for him first before dropping him off?
What do I do afterwards? I'm completely clueless. Also, I know it's kind of late but does neutering help with the marking problem? He is potty trained to go outside and use the pad but he still marks around the house.