Can I wear dresses and shorts etc?
Yes but not too short.
Are there many job opportunities? I am working has an administrator at the moment but am happy to try anything.
There are plenty of opened positions all around Doha. I'm sure you'll find what you're looking for.
Would i be able to make friends??
From the 1 million people leaving in this country (mainly in Doha) i'm sure you can make some friends.
Is there much to do on the weekends?
Weekends here are considered family days. But that shouldn't be a problem. If they see a couple entering the mall they will not stop you.
Most importantly, is it a safe country?
You needn't worry. At the moment there is absolutely nothing to fear from the neighboring countries. Just keep your eyes widely opened on the road... There are a lot of people who don't care much for the street signs.