that company casts one single alloy and provides no information on the mould composition and only a few small blurry pictures of them.
most likely they use graphite in a binder for strength and nothing like the typical stuff you can buy. it also may only work well with the one zinc alloy they use.
for lost wax, you need something to heat the mould boh to get the temperature up and to purge moisture, and also to burn out the wax. but there are several ways of doing it that dont require much gear. we usually use steam for glass moulds to remove the wax. the steaming device is a glorified tea kettle. with the right wax, you get a nice clean mould. for heating, you can then stick it in the kitchen oven. with the wax 99.5% melted away already, you wont get much fumes.
on the plaster, there are several special purpose investments most being developed for stability at high temperatures. for aluminium, you could use almost any fine plaster. its pretty easy.