"Я говорю по-русски" is a more literal translation, but it can also mean "I am speaking Russian" (at the moment). When you need to specify the languages you speak, the most common way in English would be "I speak ...", and in Russian "Я знаю ..."
I came to enjoy answering your questions :-)
Ха-ха-ха! - a laugh. Хи-хи-хи! - a giggle.
Online, Russians also tend to use a lot of brackets like ))))) when amused or ((( when sad. This may be because we're too lazy to press Shift and stretch a finger up to 6 (where the colon is). Also, changing the layout to English to type :D is kinda cumbersome.