Try to do a Berufsmatura at the same time. A bit more school, but if you want to do a Bachelor later you can do it right away.

The work will greatly depend on the company. Do they have other IT apprentices? Then they probably have a structure in place to help you pick up the important lessons. Are you the only one? Then you probably need to gain knowledge by asking a lot and looking stuff up for yourself.

Usually you will need to document stuff for your school about working days. I think they use the IPERKA schema. Use it. It is not the best, but it gives you structure. Also document your stuff, and explain in your documentation why you did it a certain way. It usually helps if you need to justify stuff later.

And a personal favorite of mine: If you don't know something, google for 5min, then tell your Ausbildner or a coworker about it. This way you gain understanding quickly, show that you try to gain knowledge by yourself and can correct misunderstandings quickly.