Australian immigration query

Hi there,

I would like to a few queries answered related to Australian visa. I am holding Indian passport and presently in UK on Spouse visa (my wife is british citizen). I have got a job opportunity for Australia and my company is sending me on business visa first and then apply for WP and change my visa there in AUS. Now queries are:

1. How long it takes to convert business visa to work permit? My WP is already applied and should be coming in next 3-4 weeks time.
2. I am planning to take my wife with me on tourist visa (while I am on business visa). Can we convert tourist visa to dependant in AUS? OR would there be any issues?
3. Would I need to come back to UK to get my visa converted to work visa once my WP is approved?

Thanks in advance,
Manoj