if you want a house your way check the fine print on buy it off the plan houses some builders charge extravigant fees for every minor change you make
if you want it drawn to suit your own ideas draw up heaps of ruff scetches and take it to a drafty avoiding the architect will save a heaps and your builder will deal with the council aproval and stuff as part of his contract
being involved in the roofing side of things i can tell you that a 22-26 degree pitch roof is far cheaper and cooler than these 30 degree plus roofs a lot of architects and builders are pushing
if your building down in the mandurah area i can recomend dolphin homes hayden brimson homes rj glossop and co and mike budd homes these are all builders i personally work for and altho a bit more pricey they give a A+ product and are good to deal with
and as for how long it takes with us its normally the supplier cant keep up with demand ive just had two days of with 4 jobs waiting cause theres a 3-5 day wait on gear