Congrats SummerGal!
Yep the peeing is probably from the IV. I peed like a racehorse for pretty much the whole day of the surgery. In fact they stuck the IV in me early, and I had to pee 2x before the actual procedure itself lol. Then right after the surgery, they wanted to make sure I didn't have any urinary retention issues (possible side effect after surgery), so they asked me to go see if I could pee ... no problem there ... I swear I peed out the entire Pacific ocean ... I was in the bathroom so long that I had nurses knocking furiously to make sure I didn't pass out :)
For me the 2nd day was definitely more painful than the first. The first day I felt like superman from the anesthesia and actually sat on my ass all day playing video games, barely felt a thing. The second day I was sore and didn't do much sitting at all. You're right to keep ahead of the pain by taking painkillers IMO. Eventually you'll figure out whether you need painkillers, what kind, and how often, but better safe than sorry the first day or two if you ask me. Some people take opiates for a while after surgery (I did), but most only need them for the first couple of days.
Docusate sodium is a stool softener. Common brands in the US are Colace and Dulcolax. It wasn't very effective for me so I stuck with Miralax. I would say that if your current stool softener (I don't know what kind you're taking) is working, then stick with that. When it comes to diet and stool softeners, it's all about what works for you as an individual. If you have a winning combo already, I'd be inclined to not mess with it. Just my opinion of course.
The first poo is always the biggest fear after surgery. That's almost universal and entirely understandable. For me it wasn't too bad. Some pain, but nothing in-your-face like a fissure (bear in mind however that I had less work done than you did). The Fleet Enema I used right before surgery was WAY worse than the first poop. The enema thing stung to no end, whereas with the first poo (and actually the next few poos after that as well), my main disappointment was that it didn't feel like I was voiding my rectum completely. My turds came out in little pieces and it annoyed me that I couldn't just drop a nice big monkey tail and get it all out at once. I've heard similar complaints from others too.
The worst is over, and once you have that first turd, I think you'll feel a lot more relieved (pun intended :)). Recovery itself can sometimes be an up and down process, but you'll get a handle on it soon enough.
Cheers to your new caboose ... choo choo!