"What's the pay like in Nigeria? Tax free or paid............"
Taxes are something that is between you and your Government. If you live in Canada you will qualify for a tax credit that simply put will reduce your taxable income by about 80% on the first 80'000 CDN dollars you earn.
To be tax free in Canada means you are not a resident. So then the question is where are you a resident of? If the answer is Dubai then you are indeed tax free. If the answer is Germany then you are most certainly not.
Some countries have lenient rules regarding non resident tax status (like Australia) and some (like Canada) are very stringent.
I'm a year out of date on the pay in Nigeria or anywhere else at this time so I won't comment accept to say it is more than you will make for any of the companies in the sandbox.
The pay is in CDN dollars which are worth about 20% less against USD then they were two months ago.