Dear friend,
For certifying your degree certificate, you have to approach the Qatar Embassy with all originals. There are agents doing this, but it's risk to give the originals to the lay men. They are charging Rs.5K to 10K. It's better to go personally. It takes time to get it checked from edu institutions and attest it. Pls check whether it's needed for Qatar. It's normally asked in UAE.
Regarding the marriage certificate, the original one is not having legal validity for whole life. The notary public certificate with photos of husband & wife signed by notary public is of good legal value and is enough.
Best wishes!

Kannan.