After the keypad come out;
the 'upper left corner' will has a keyboard icon;
pull down the menu;
click the 'Select input method';
if 'Chinese keyboard' is selected, choose 'Configure input methods' at the bottom.
then click the icon next to 'Chinese keyboard'.
Then you can find and set the handwriting for Chinese.
And for the lagging, wait for 2 - 3 days first, if it still happen, then try to reset it. Coz it even stay that on their site that it will happen at the beginning (happened to me too), then the ICS will work better (and the battery last longer too).