What kind of windspeeds do you have there in Hong Kong?
What are the sea conditions where you intend to learn to windsurf?
Unfortunately, the "cross over" from dinghy sailing to windsurfing may not be
as easy as you think.
Take CC's advise, and get some good lessons on the basics.
Then depending on wind and sea conditions, look for something like a Rio
or Go to get you started easily when you have determined that you really do want
The reason for the wider board is stability and the ability to get planing earlier.
If you have very light winds there, then the Rio (with a retractable center board) might be the way to go as sailing true shortboards (no centeboard) in sub planing conditions isn't going to be very much fun.
If you want a lighter weight board look at the larger Futura as they are the same basic hull shape as the GO and are quite fast and easy to sail.
The Kode TufSkin 122 might be OK to start out on after lessons on larger wider boards, but you will need at least 12 knots and a 7.5 m2 rig to get planing on the Kode 122.
The removable center fin could help in sub planing conditions, but it's too small to be of
any real value in staying upwind, and the board won't plane very well with the center fin installed.
A 122 liter board with a 70 Kg. sailor is going to be very tippy and a bit unstable right at first.
If you get good lessons and get the basics learned, then the Kode would make more sense.
Hope this helps,