If I sue my former landlord for taking an extra 150 € from my deposit and I win, besides from the money they should give me back (the 150 €) should they pay for my lawyer expenses?
Or is there a small court for this cases where I do not need a lawyer?
According to this European Judicial Network summary Austria doesn't have a special court for small claims such as this, but the main civil procedure in the District Courts allows for such claims to be brought with appropriate accommodations for their small size – including permitting you to forgo legal representation.
The same page indicates that awardable costs in all civil cases are linked to the size of your claim. I don't know if this reduces to zero for such a small claim but it would certainly not make any sort of dent in the cost of legal representation if you chose to pay for it.
The answer to this question varies depending on the jurisdiction, in most places, the losing party pays all legal fees necessary to the winning party's case. This principle is called "costs follow the event"
Most of the time, there are exceptions to this rule where: the winning party unnecessarily incurred costs, where the winning party rejected an offer to settle for an amount greater than the amount he won at trial, and many other factors.
You will have to check how costs are determined in Austrian civil law, to see if the above general principles apply, or if Austrian law does things differently. A good starting point would be the Austrian version of their civil procedure rules.
