Alex -
My wife and I were in Beijing in early October last year, so our experiences are rather recent.
Be prepared for crowds - everywhere. Also, be prepared for vendors who will try to sell you anything and everything. They are especially obnoxious at major tourist attractions - the Forbidden City, Great Wall, etc.
Probably one of the best things to do would be to arrange for a formal tour. The principal sights (Forbidden City, Summer Palace, Ming Tombs, the Hutongs, Great Wall, Prince Gong's Palace, Garden of Heaven, etc) are scattered about over a rather large geographic area. There is probably a practical limit to the number of things you can do in one day, and a tour operator can put together a schedule over a period of days that will get you to the main areas of interest. You will spend lots of time in traffic - that's just part of Beijing.
If you do arrange for a tour, be prepared for the fact that the tour operator will include some shopping opportunities whether you want them or not. There seems to be a requirement that tours include jade factories and pearl shops.
The one thing that I bought is a chop. They are inexpensive and can be made to order just about every in Beijing - including at the airport as you are waiting for your departing flight.
I didn't have any concerns about my camera during our visit. Frankly, if you have a film camera, you will probably be in a real minority - it seemed to me that the Chinese have completely digitized.
I also didn't have any actual concerns about pickpockets. The last trip of this sort that we took was to Rome in 2000, and we had a "close encounter" with pickpockets on that trip that was unsettling. Being surrounded by hawkers in China trying to sell various things sometimes can feel intimidating, but I never felt that there was any threat of theft.
There are specialty restaurants in China, but the traditional Chinese meal includes seafood courses. In fact, the tradition in China is that the last course of a good meal is always the fish course. Our tour operator had arranged for lunch, and the experience was mixed. Some were good, while others were pretty grim (especially the "famous" noodle place in the National Museum across the street from Tianamen Square).
Our son lived in Beijing for three months last year (not while we were there, unfortunately), and since he is very adventuresome about food, he thoroughly enjoyed the experience. I'm not sure that can accept that deer penis is edible.
Weather in early October will be moderate - cool enough in the evening that you will appreciate a light jacket, but warm enough during the day that you won't need anything. We had one day of pretty bad smog, but the rest of our stay was very bright and sunny.