Hi,
Do I need an agency to find a job or can I go direct?
You can do either. Some people get better results (= find a job) by using an agency, but employers do prefer you to apply yourself, as the agencies charge huge fees.

I don't know anyting about getting visas/ permits, but you cannot convert a visum into a permit. They are two different things.

Also don't know how difficult the exams are. That might depend on your recency of study and study contents, etc.
There are posts from study groups in this section of the forium - just check those, they might give you more information.

Regards,
Fyzzio