Pixie, there are some really good detailed descriptions of elec CS's on the childbirth board if you want to get more info -
www.mumsnet.com/Talk/childbirth/954494-Support-thread-for-those-of-us-who-are-requesting-an?reverse= 1.
Lovethesea wrote a fantastically detailed and easy to read account of her recent CS a couple of days ago.
A elec CS shouldn't involve anything vaginally intrusive (no exams/instruments) - there's no need. However, you will need to have a catheter inserted via your urethra into your bladder. You can request that this is done after you have been given your spinal/epidural, and also when the surgical screen is already up and across your body, so you are numb and don't need to see it.
As others have said, catheters usually stay in for 24 hours, and during this time, obviously knickers aren't practical because of the catheter tube. They might have you lying on an absorbent pad, with a maternity towel 'wedged' in between your legs to catch the bleeding.
You may also get a painkilling suppository up your bum! Again, this will be done while your epidural/spinal is in place, and with the screen up, so you don't need to feel it or be aware of it.