* Is it hard to find a flat or a house for rent in Graz?
as usual it depends on what you are looking for
and how much you are ready to pay ... but generally
i'd say yes.
* How to find a home in Graz: classifieds, real estate portals, real estate agencies?
BTW: If you want to efficiently navigate
these places it really helps speaking German.
* How much is the rental for a house, an apartment?
Depends on the size/location ...expect, for example,
to pay approx 700 euros (including all bills) for a
well-maintained 1BR (60 square meters = 600 sqft) apartment
in a central location. The further away from downtown you
go the cheaper it gets, but the differences are relatively small ...
any apartment of this size below 600 euros (including all bills)
is most likely a dump.
* What are the formalities or the required documents for renting an accommodation?
if you are a foreigner a passport should do. Some documentation
about what/where you work and about your salary will certainly help.
In most cases you are expected to pay a deposit of 2-3 months
(net)rent up front. When you move out, you'll get that back
minus compensation for any damage to the property you might
have caused. (possibly plus a moderate interest rate - if so
make sure that his is stated in the contract)
I've heard of cases where the landlord kept the deposit
in spite of the place being kept immaculate, and people
had to sue or forgo the deposit, but these are rare exceptions.
If you employ the help of a real estate agency with a large
(well-lit) office in downtown Graz this will probably minimize
the risk, but often comes at the price of an expensive commission
and/or transaction fees.
* Which advice would you give?
real estate agents often charge high commisions ("provision",
up to three times the monthly rent). If you want to avoid that
try to find something that's offered directly by the owner,
or at least try to get a bargain (some real estate
agents are ready to negotiate)
at you can choose under "Filter"
to look only for places that are offered without commision
("provisionsfrei")
at you can buy a (fairly cheap) monthly
subscription which allows you to view ads online a day
or so before they are published in print.
west of the river Mur rents tend to be a little bit cheaper
as this area is considered less up-market than the east,
if you compare rents for different places be careful not
to compare apples and pears, i.e., rents are often, but
not always, quoted including general maintenance fees
(haus-betriebskosten) but excluding bills, sometimes
heating and/or hot water is included sometimes not, etc...
make sure to have a good look at the apartment, to get a contract
signed, and to see some ID of the other party BEFORE
you pay any deposit. (Rare) cases of fraudulence have been
reported.