What to do with car insurance?

[RepSpec]

hey all
just got my car insurance renewal and am just curious about a few things.
car is a BA mk2 wagon on gas, no mods. im 23 turning 24 in december. just car offered me just under $1000 for; full comp with excess of 500 and age excess of 600, for car value of $13,600, with rating 1 for $35.
i had a look around quickly and they were reasonably priced, but there were others cheaper.
question...
-do people use insurance mobs like budget direct or "non big brand" companies ie aami, racv ect. or should i just stick with just car?
-once i turn 24 will i still have to pay the 22-24 600 excess?

cheers