About how far to QSY - We tend to fill the "5's and 0's" first. Only
when the band gets busy do we "splinter", so the short answer is, QSY
a minimum of 5 kHz up or down. 10 kHz is better if you have identified
locals using the "call frequency".

Yes, it is a good idea for one of the QSO partners to go off and check
that the "landing zone" is free, but if you have done a recent scan of
the band, speculative changes are not unheard of.

On VHF, as Bert has hinted, you typically congregate on your (best)
local repeater fequency. It's good practice to go to a simplex
frequency after making contact if you can.

Don't get hung up on tones, etc.  They are rare in Australia. The WIA
repeater listing will tell you if you need one.

As far as procedures go, we don't tend to call CQ on VHF. We simply
announce that we are monitoring. Other than that (and going to simplex
if possible), procedures are pretty much the same as HF.