Can I demand a c-section?

Yes. As long as you understands all the risks associated with a cs and your ob/gyn is willing to perform it, you can ask for it and most physicians will comply.
Sure. The evidence about c-section by maternal request (not "demand") suggests it is a reasonable option for most us women looking to have 1-2 children. Your ob/mfm physician has to agree for you to have one, however second/third opinions from other obstetrical surgeons may be vecessary if you disagree with your physician.