No, domestic mail does not have to be addressed in Chinese characters.
When writing in English/romanization, the format is basically that of the United States (and probably most other Western countries). For example:
[quote]Chen Zhi-ming
55, Ln 77, Sec. 2, Jinshan S. Rd.
Jinshan, Xinbei 10603[/quote]
As for directing the mail to someone’s attention, that might depend on the English ability of the organization receiving the letter. But just having the person’s name should work fine.
It’s a good idea to go with the 5-digit rather than 3-digit postal code whenever possible, as that reduces the chance of error.