We'll be in Xiamen from Jan 4 - 7, 2013. Please suggest must sees, must dos and must eat ins.

Anyone going there will never miss the Gulangyu Island and South Putuo Temple, which may impress you a lot.
In my opinion, you cannot miss the colorful nightlife there. KK Disco Pub at No.9, Lianyue Road and Jurassic Bar at No.221, Binlang Road, Siming District may be good choices for you.
Apart from delicious seafood, the local snacks cannot be misse, such as Tu Sun Dong, Spring Roll and Peanut Soup.