Train
A train ticket from the Vienna Airport to Linz may cost from around 14 EUR to 45 EUR, depending on the offer you choose. The Austrian railway company ÖBB offers 'Sparschiene tickets' which have reduced price, and usually appear in the App 'ÖBB' weeks in advance. So, you can easily book a good ticket online several weeks prior to your departure. Please, note, that the ticket doesn't assign you a seat automatically. Place reservation is not necessary in Austria. However, if you are afraid that there will be not enough seats, you can add place reservation to your booking.
Another useful tip for you, before using ÖBB services, is buying a Vorteilscard, which gives a 50% reduction on all ÖBB full-price tickets. It costs around 20 EUR (for youth), and is valid for one year.
Bus
Most likely you won't need any public transport if you live in Steyr, Wels or Hagenberg. However, in Linz you will, as it is the 3rd largest city of Austria, which even has an Airport. The city infrastructure is so well-organized, that Linz has won a European Award for Smart Tourism. The fact that Linz was chosen to be the European Capital of Culture in 2009 is testimony to its rich cultural life and its general convivial atmosphere.
Students can apply for an "Active pass", and the public transport ticket would cost then just 13 EUR/month. A regular monthly ticket for all types of public transport in Linz (Linz AG Linien), called 'Transferable monthly pass', costs 46,20 EUR.
Food/nutrition
Austrian cuisine is composed of influences from Central Europe and throughout the former Austro-Hungarian Empire. Austria is proud of its coffee houses and restaurants, called 'Gasthaus'. In a typical Gasthaus you can get a big meal (for example, Schnitzel mit Pommes) for 9-10 EUR. If you know how to cook, your monthly nutrition budget will be around 160 EUR. To be mentioned, such low-cost supermarkets as Hofer and Penny have very friendly prices.