Hi,

well it depends on your residency/visa status. Are you comming with a business visa only, or you are getting local employment contract. If it's just business visa, I don't think you can open a bank account. See the requirements here:
https://www.iloveqatar.net/news/general/how-to-open-a-bank-account-in-qa...

I think you won't have much opportunity to exchange QAR outside Qatar, as foreign banks ceased trading them just after the siege started last year and not sure if it has changed since.
Therefore your only option would be to exchange QAR to EUR here in Qatar and take your cash home.