My parents are both Deaf and I grew up with many Deaf and hearing impaired friends.

The Deaf community in Australia is very strong if you are interested in being a part of it. AUSLAN is a great language and even though he's only hearing impaired I'd still encourage you both to learn. It can help immensely in the future as it is a method of communication. I have a few friends who are hearing imparired and were never taught AUSLAN. When they got to mainstream schools, their hearing and speech wasn't good enough to learn or communicate. As such they had no way of communicating with people and then had to learn AUSLAN as teenagers.

Sorry if this is rushed, I'm finishing work now. PM me if you want more info or just to chat.

Fiona