I had an unplanned Csection after many of hours of labor, and recently a planned Csection. The planned one was a LOT more 'pleasant' than the unplanned one because with the unplanned, I wound up having the shakes during surgery and for hours afterward, which, the doctor said, was likely due to the labor beforehand. This time, with the planned, I had no shaking so it was so great in comparison, and I've heard from others also that planned are much better, so that's good news for you!
Also, with my planned Csection, the epidural was not too bad - you sit on the operating table, hunched over, and it is an in/out needle - not too horrible for a diabetic! (As opposed to with my unplanned, I had an epidural drip in which stayed in the whole time).
After the surgery, I was scared to take a shower and get the water on the cut, but surprisingly, there is zero pain with that, I guess because it's all numb down there, but showering never stung at all.
The first 24 hours after surgery is the worst while your legs come back to life, but the pain was not bad - I took the pain medicine each time it was offered for the whole time i was in the hospital (or asked them for it when it was time). During surgery you can't feel anything except weird pressure but it's definitely tolerable, plus the surgery is only a few minutes.
I wasn't able to breastfeed for about the first 24 hrs with both babys (they kept them just to watch their blood sugars/ annoying), and I had trouble getting them both to latch on and eat for about a week, so i pumped and my milk still came in fine and they learned how to drink from my boobs once the milk came in (which feels like your boobs are turning into rocks, btw!, but only for like a day!)
Diabetes-wise, the hospitals (both times in NY, different hospitals) are annoying about watching your blood sugar. They agreed that I could take my own insulin but tell them when I was taking it/how much. Also they were very concerned (ie, a bunch of doctors would run over) when my sugar went below 70 (it was 69 once, not such a big deal to me but it was a big deal to them). They were not concerned though unless my sugars, on the highside, were above 200 (which was weird being they were so concerned about it being low during the whole pregnancy). They took my blood-sugar every hour for my first kid, every shift or so and when i ate for kid2. And I wore my continuous meter (dexcom) during the surgery and entire time, even they first wanted me to take it off but I insisted I did not want to (and even though the doctor I had been seeing said it was fine for me to wear it they didn't care).
You should ask the nurse lots of questions - like how to get out of the hospital bed most easily (that's hard at first while your legs become un-numbed!). And lots of questions about breastfeeding, diapering the baby, etc. Being able to be in the hospital longer to ask questions to learn how to change a diaper, breastfeed, etc was definitely helpful.
Yes, I know how you feel about wanting pregnancy to be over. The last weeks drag especially being i had a 10lb 1oz-er!
Good luck, you'll be there in no time!