Can anyone tell me whether one can work in Lagos/Nigeria as a Freelancer in any field? If yes, then under which visa category it is allowed and what's the procedure for obtaining this type of visa? Does one require a local sponsor for even this type of occupation? What will the level of earning need to be to break even in Lagos?
To become a freelancer in Nigeria, you'll need to apply for a business visa and for this you'll need a Nigerian sponser. You can read more about the procedure on the Visas for Nigeria page.
The cost of living in Lagos is very high. The city was 39 out of 214 in the 2012 Mercer Cost of Living Survey. Accommodation is particulary expensive.
For a full breakdown of costs you should read the Expat Arrivals Cost of Living in Nigeria page.
Good luck and let me know if you have more questions.
Shantalie
According to the Nigerian High Commission in London's website you sponsor can be a person or organisation. However, I would just call the relavent embassy in your home country to confirm this.
I am unable to find any document that states exactly the amount of money needed to apply for business visa for Nigeria - official documents just says proof of funds. So again, I think it would be best to talk to an official at the embassy for advice.
Good luck
Shantalie