You will be fine, in fact, you will be amazed that everything you hear on TV is basically wrong when it comes to Saudi Arabia. People are friendly and you will run into many Europeans and in no time you will have friends over here, both locals and Europeans.
Saudi is a big country and depending on where you are planning to go, it might be really cold or hot, so check the weather and be ready for that.
Regarding government paperwork, almost everything is electronic, this includes opening a bank account and so.
English will be more than enough for you. Almost everyone speaks it to a different degree.
It will be a good experience, try to enjoy it.
Source: I am a Saudi, who has a lot of European colleagues and friends.