There are many fun places, but LZ~ you only have two days. Then I suggest you go to Victoria Peak + Madame Tussauds Wax Museum, Tsim Sha Tsui Promenade + Space Mission + Avenue of Stars. The former takes about 3 hours to see including the distance; the latter takes at least 2 hours due to its wider area. Also, Harbor City next to the Star Ferry Pier in Tsim Sha Tsui is a shopping hotspot.
To buy cosmetics, just go to Sai Yeung Choi Street in Mong Kok. There are many chain stores such as Sasa, Bonjour, Angel, ColourMix, etc. on the entire street, as well as brand stores such as H2O and Fancl, which are enough to keep you shopping for most of the day.
There are delicious places almost everywhere in Hong Kong. If you want to try snacks, go to the one next to Xianda Plaza across from Sai Yeung Choi Street. There is a restaurant there that sells fish dumplings, siomai, and fried snacks, which is very famous. There is also Hui Lau Shan nearby.