Will it be uncomfortable to swallow the camera to view my stomach lining?

Yes, but normally not painful.

"Anesthetic in a liquid or spray form will be given to you to prevent gag reflex. You will lie on the examination table and you will probably get a sedative medication as an injection into the vein in your arm – this will make you drowsy but you will remain conscious. During investigation you will lie on the back or on your side. Doctor will insert gastroscope through your mouth and proceed it toward duodenum and then he/she will slowly pulling it out and observing the inside of the duodenum, stomach and esophagus. If necessary, doctor will cut of few small pieces of tissue (biopsy) from the inner lining (mucosa) as samples for further investigation under the microscope. The procedure takes 20 minutes to an hour depending on what needs to be done.

How Does It Feel?
Upper endoscopy should not be painful, but can be quite uncomfortable. You may experience choking (desire to vomit). Breathing should not be affected. Procedure is usually not painful but you may experience some cramping.

You will need an hour or so to completely wake up after the procedure. You might feel nauseated or have sore throat (may persist for few days). You are allowed to eat and continue with medications right after that."
Source and further information:
http://www.healthhype.com/upper-endoscopy-gastroscopy-procedure-video-pictures-cost.html

Further information:
http://en.wikipedia.org/wiki/Endoscopy

Yes it will! but if you need to have it done then it's best just to put up with it! My Mother needs to have the same procedure but she is very scared of the discomfort too, I had a friend of mine visit her who had the cameras down some months ago, he explained everything to her & reassured her that the staff at the Hospital are very professional & understanding to patient anxieties & helped him overcome his own apprehension, he did say he was glad he had it done as he now knows he's treatable with tablets & not surgery which would have really terrified him! :-/

If you mean an Upper Endoscopy, no, not at all. I have a history of ulcers and gastritis, and I've had that done twice. Both times I was given something to "relax" me, but I actually was completely out during the procedure. I didn't have any soreness in my throat, either, as I had been advised was a possible side effect.

No, from what I hear its not too bad.