Hi Natalie
I would agree with Elizabeth. Exchange, short term study and international students are three separate programmes with separate regulatory requirements.
Short term study students only require a tourist visa with up to 3 months study available on the visa. That sounds like what you are after and doesn’t require any special overseas student programme registration. I agree with Elizabeth that referring to it as a cultural tour rather than an exchange is wise. CRICOS and Exchange (AASES) programmes are federally regulated and will affect you in Tasmania as well.
I would suggest a separate application form and always have the biological parents sign an offer even if it is an amended one re fees/ dates etc. We used to treat host families the same way our long term international students were treated so host families had access to day to day excursion notifications etc. It’s the only way they can have the students where they need to be on time etc. On your letter of offer there needs to be a blanket statement advising that a homestay family will be arranged by the school and what those arrangements will be. We then had homestay profiles and student profiles that were provided on both directions to student and homestay.
I hope that helps.
Trish