The usual response is to applaud back. In China the family name is always mentioned first. It is customary to arrive a little early if invited out socially. Toasting at a meal is very common, as is the custom of taking a treat when visiting someone's home, such as fruit, confectionery or a souvenir from a home country. If it is the home of friends or relatives, money might be left for the children.
Stamps are also very popular as gifts, as stamp-collecting is a popular hobby in China.
A good gift for an official guide is a Western reference book on China. Conservative casual wear is generally acceptable everywhere, but revealing clothes should be avoided since they may cause offence. Places of historic and scenic interest may be photographed, but permission should be sought before photographing military installations, government buildings or other possibly sensitive subjects.