I have had two c-sections in two different hospitals and by two different doctors. The first one was an emergency and the second one was by choice. Okay, so now to answer your questions.
I would guess that the nurse tries to place the catheter before the spinal is done. I believe this is normal procedure. With my first child they induced me and I was on a pit drip. Back then you were only allowed to have a pain shot once, maybe twice before your spinal was done, and they wouldn't do the spinal until you were dilated to a certain point because it didn't last that long and they wanted to make sure you were as comfortable as you could be during delivery. That isn't the case now. Everyone knows that contractions are a lot harder, come closer, and hurt a lot worse when you are on Pitosin. Well when I was in the middle of a contraction, which were coming every minute or two at the most, the nurse tried to place a catheter. I had never had one before and putting a catheter in while you are in the middle of a contraction is very painful. She tried it again but my contractions were coming so fast and so hard that she really didn't have much of a choice. After the second attempt that failed I told her I was done and wouldn't allow anyone to do it again until I had my spinal. The doctor that I had then was a very nice guy, he used to date my mom as a matter of fact. He agreed to place the catheter once I was no longer able to feel it.
During the birth of my second baby I told the doctor from the very first appointment that I refused to have a catheter placed until I was numb. He said that sometimes isn't up to him but to the anesthesiologist. So I told him that he needed to ask him and find out or I would need to find another doctor. By my next appointment he had talked to him and they both agreed that the catheter would not be placed until after my spinal took effect.
The next question you ask is can we feel the catheter going in after the spinal meds have been given. Hell no. Think about that question for a second. They are getting ready to slice open your belly, clamp your skin back, use both hands and reach inside of you and deliver a baby. If you could feel a catheter going in then how in the heck are they supposed to deliver that baby if you can still feel things. Again, hell no! I was numb from about the bottom of my rib cage all the way down from there. Thank god!
Your last question is how do we feel being all exposed in front of the doctors and nurses. Most pregnant women by the time they get to the point of delivery whether it be natural or c-section don't care who sees them. We are usually to tired, nervous, excited, or scared to give a crap about who sees them. We are moments away from seeing and holding the baby that we have been growing inside of us for 10 months. Prior to delivery, especially natural or non sectioned births, all the nurses and doctors have been looking at and sticking their hands up inside us checking on how far we are dilated and what not that when we are again exposed we just don't really care. Besides that, doctors and nurses are professionals and they see nakedness all the time, and they don't care.
I hope I was able to answer your question appropriately.
Mashie