The temperature is around 20C degrees with little rainfall. So, it will not be cold although sometimes the days are changeful. A thin sweater and tee tops are enough. There are lots of shopping malls in HK, so which part you favor? Tsim Sha Tsui or Causeway Bay? At the Chongqing Dasha of Tsim Sha Tsui, you could find many hostels or home inn.

I prefer the Kowloon side

So. hotels in Tsim Sha Tsui, Mong Kok and Yau Ma Tei are what you need. Besides these in Chongqing Mansion, I know one hotel called Bridal Tea House Hotel located in Yau Ma Tei.