Surgery was, for me, a breeze.
Only my experience...
Pain - Assuming, with good reason, you will have LAR Surgery with a minimally invasive approach the pain will also be minimal. My surgeon was utilizing a quick recovery approach which included absolutely no narcotics and honestly they werent needed, I was home two days after the surgery.
The front exit - Your ileostomy will be a temp bag out of surgery, the nurses will come in and give you a real one most likely the day after surgery. You will be asked to keep track of the output before they let you out, same with urine after the catheter. While I am sure you met with an ostomy nurse pre surgery I took a video of it just in case asking multiple questions along the way. It helped when I got home to refer to.
Recovery In the Hospital - This means walking, walking and more walking. I was up about 6 hours after being put in my room. Progress through the liquid diet, then soft foods and normal foods pretty quickly. Catheter should be taken out day after surgery as well. Also, kinda nasty, there might be stuff continuing to come out your backside while in the hospital for which you will have no control over. The nurses and doctor say its fine and it is, dont sweat it.
Misc - You will most likely get a wound bulb that collects liquid you will have to empty periodically but its a nuisance rather than a problem.
Back Home - If you are not a good back/side sleeper get used to changing that. For the first 2 or weeks I could only sleep on my back because turning to my side was painful and obviously you cannot sleep on your stomach. A good recliner is great for the first week or two until you dont have pain when turning and then you can go side sleeping(either side). I dont smoke but was a caffeine addict, that becomes a no-no at first because your dont retain water as the colon goes offline where our water is normally recycled. The ileostomy will take some time to get use to and the biggest surprise to me was the smell, it smells far worse than a normal bowel movement.
Overall dont be worried the surgery it is the least problematic or traumatic thing to get through. The radiation pain was far worse, the folfox clean up(in the dead of winter) is far worse, the pain of getting your ileostomy fitting wrong and getting severe irritation is worse. If I was given the option to do the surgery every three weeks or my current chemo I would take the surgery, that should say something. I am not looking forward to LARS either but we do what we must to tackle this beast.
You will be fine