Visa rules on runing a business while working

Hi

I am looking for some answers to couple of my questions:
I am here on work visa and my wife is under my sponsor.

1)can she start up a business under her own name. i.e 49% share in limited liabilty company.

2)During the intial stages of business untill it starts to generate reasonable profit, can she work for an employer on part time/full time basis

would like to know the visa rules on the above two, wonder if any one can shed some ligh on this.

many thanks in advance for your input

have a good day