urgent--Taiwan Visa

I am holding a Canadian Passport but living in Hong Kong. I had
been to Taiwan with the old Taiwan Visa ten years ago. I plan to go to Taiwan next week.

Do I need to apply for Taiwan Visa in Taiwan airport or in Hong
Kong ?

How long does it take to apply for the Taiwan Visa for re-entry in
Hong Kong?

I plan to go on Aug.15. Is there any faster way to get the Taiwan
Visa?

Thanks very much.