It is very easy to get from TST ( Kowloon-side) to LKF, Soho, Wan Chai (Hong Kong-side) by taxi, bus, ferry, and MTR (underground electric rail)
NOTE: the ferry stops running about midnight and MTR about 1am. A cross habour taxi using the "old tunnel" from LKF, Soho, Wan Chai to TST costs approx. HK$90 to HK$130 if minimal traffic.
Some of the many TST Hotels are: Nikko Hotel, Marco Polo Hotel, BP International, Holiday Inn Golden Mile, Intercontinental, Hotel Miramar, The Miden, Kowloon Hotel
There is nightlife in TST - such as Knuttsford Terrace, 1 Peking Rd and Ashley Rd, Minden Avenue -that you can check these places out too!
I suggest that you look at HK Magazine either online (www.hk-weekend.com) or BC Magazine (http://hk.bcmagazine.net/) They are free magazines that come out each week - suggest you get a copy of them when you arrive.