No idea how that quantifies against a BOC cylinder in terms of quantity, but it seems cheap enough. But yes pure Argon is what you want.

The machine may or may not come with a regulator and flow meter. If not, you need one.

I think it was a no 8 FUPA cup I bought which is suitable for both Alu and steels, and I use 2.4mm tungstens. I cant comment on how good or bad various colours are other than I recently started using blue and it seems fine vs the gold I tried before.

Do not compare UK/Euro colours to US videos, as they seem to use different colouring.

And I think it's 5032 is the generic filler rod for Aluminium, again 2.4mm diameter. 4043 is more towards cast welding. ( not sure on exact numbers from memory though.

Really..best to try and get all the consumables from one place, after speaking to them.