Hi, MC

I am self from south africa and are also trading - To start the first thing to do is to get somebody to trade through - Somebody where you can open your trading account - There is a lot of people that`s doing that and you should just watch out that you don`t pay to much or any extra fees - A trading account should be free and you should make sure that the pip spread is very low.
You need about $200 to open a mini account and for a regular account about $1000 - After that you need to start to learn to trade good but that isn`t necessary if you use good forecasting software - Try http://www.forexforecast.co.za - They are good.
For taxes - It`s your own responsibility to pay tax - The money you make you can put in your own bank account or you can keep it offshore and then just draw it in South Africa from a bank that supports the account.
It`s all up to you.

Cheers