Brie:
It's not a shared 3-bed apt. It's a 3-bed apt for each pilot although many are only getting a two bed and I believe a very small few are getting a one bed apt. However, the company will (after you apply and reach the top of the list) provide an accommodation allowance which is more than enough to live very comfortably in a 4 bed villa in many areas of the city.
In regards to your query about whether to go for ryanair or Qatar; being your first job, either would be a fantastic start for your career - jet job and quick hour building. Each have their pros and cons but I believe the decision here should come down to your life outside of work. Ryanair will leave you with little money left over once you are paying taxes, housing, loan repayments for type rating etc. Qatar will pay you well enough to allow you to take advantage of the staff travel and enjoy yourself outside of Doha if the lifestyle there is not your 'ideal' life - I have spent 2 years really enjoying life in Doha. Friends and an open/proactive mind will allow you to enjoy sandpit life.