Howdy WW,
The standard shipping method for Australia would be the United States Postal Service - Priority Mail. This service takes around 6-10 business days, but perhaps a bit more as we head toward the holiday season.
Delivery for the SEX amp can vary between 3 and 6 weeks, with perhaps a few instances where an out-of-stock part holds us up a little longer than anticipated, and there's always the madness of the holiday season! For a safe arrival before Christmas, I'd imagine ordering by the third week in October would give you a giant of safety margin.
As far as tools go, the SEX amp doesn't require anything too out of the ordinary. A 40 watt iron, solder, needle nose pliers, wire strippers, wire cutters (small cutters), a volt/ohm meter, and an assortment of screw drivers would be enough to build this kit. With careful shopping, you can get all of this for under $75 in the US, even less if you go second hand.
-PB