Would have thought Business Visa was to allow them to come to Qatar to conduct business on behalf of a company whom he worked for outside of Qatar. Wouldn't imagine it would allow them to get a job in Qatar as you need a Work Visa for that.

Would therefore imagine that if they tried to convert a Business Visa to a Work Visa it would be very difficult. I know my Work Visa couldn't be processed as I was here on a Tourist Visa at the time, to decide if I wanted to come here.

As such I would imagine a Business Visa would be OK for renewal almost immediately but I could be wrong. However I do not believe they could take up employment on it, unless starting their own business as an investor.