Hi Sizwe. Aside from some of the obvious responses and answers that you’ve already received – which by the way I agree with – I think that since you are located in Johannesburg, the answers to your questions (especially regarding the issue of pay) is best asked of sources much more local to you. As I’m sure you are aware, employment issues such as duties, pay, benefits are much more locale specific than what most on this forum can effectively respond to.
Your question leaves a out some very important information such as, since you yourself are an independent contractor, is your assistant an actual employee or also an independent contractor? Are you offering this person ‘other benefits’ aside from salary? Many more questions as well.