In China, serving tea when guests come is a very traditional propriety. It is a significant way to show respects. In the wedding, this act is in respect and gratitude to her parents for all the years of love and care. Besides this, tea ceremony is much meaningful in a wedding. Tea is the symbol of purity, stability and fertile. The purity of tea represents the love is pure and noble; the stability of tea stands for faithful love; the fertile of tea represents the family will have many children.
It's very hard to give you an indication of what amount is suitable as it really depends on the family situation and traditional practice. This vary widely across families and different regions in China. If you're not sure, you should ask someone in the family first. It's better to be embarrassed asking, then feeling embarrassed when giving a too low amount.
To decorate the room for the Chinese wedding tea ceremony is also a good choice. Gold and red colours ‘Double Happiness’ symbol, Chinese marriage gods, phoenix and dragon motifs and decorative strands of firecrackers are all suitable for the ceremony.