i've had 6 abdo ops in my lifetime, and that pre-op scared feeling never lessens, it's normal.
just try to relax, consciously tell yourself you're in safe hands and these surgeons do these operations day in day out.
i would also agree that the PCAS system is amazing - i've had ops without it and with it, and would definitely insist on it if i need surgery in the future... it just gives the right amount of painkiller to keep it on a level, you can't overdose on it, and you don't need to wait for nurses to be free to bring tabs or injections.
i think i did wake up with a NG tube and a catheter each time, you may also have a drainage tube in your tummy.. don't be scared by all this - it's normal...
days 1 & 2 you'll probably be very sleepy, and it will hurt, especially when you move.. by day 3 i would expect the staff to be helping you get out of bed into a chair, and maybe a couple of steps. they'll have you on nil orally to begin with, then sips of water... you can ask for a mouthwash swab or an ice cube if your mouth is dry.
just keep telling people what you're scared of, what you're feeling, what you feel you need... even if it's a couple of minutes of their time just to cry or talk or whatever - i've always found that the nursing staff on surgical wards are wonderful.
you'll be fine, and will feel so much better once the initial recovery is past. i'll be thinking of you.