For all that stuff except the default material, you can create maxstart.max in your default scenes directory... every time you hit reset, it'll load maxstart.max For the default material I think you have to create script / callback.
Take this code, save it as "defaultmaterial.ms" and place it in the scripts/startup folder, now every time you create a new object it'll apply the arch and design with a random color (feel free to modify this) --I haven't tested it much, so if you have problems, you're on your own... but it should suffice.
fn assignnewmat =
thenode = callbacks.notificationParam()
themat = Arch___Design__mi()
themat.diff_color = color (random 0 255) (random 0 255)(random 0 255) --you can modify the default color / add lines for other defaults
themat.name = "ArchDesign" + "_" + thenode.name --can modify the name of the material
try(thenode.material = themat) catch() --try/catch in case of some wierd object that it might screw up on
callbacks.addscript #nodeCreated "assignnewmat()" id:#archmatcallback