Never heard of a Nigerian goat but I have owned a couple of Nubian goats and yes they do have upper and lower theeth.
A pygmy goat is slightly bigger then the Nigerian dwarf. Pygmys are like walking barrels, they are shorter and heavier. Nigerians are a little taller but slimer.
A wether is a male sheep or male goat that has been castrated.
They both only have top molars, a full set of bottom teeth and you are able to tell the age by the teeth.
There is no such thing as an African weather goat. A whether is a male goat that has been castrated. There are many different types of African goats. The smallest goat is the Nigerian dwarf.
The scientific name of the Nigerian Dwarf Goat is Capra aegagrus hircus.
Philipenio japoro
A urinary acidifier
Yes
It would depend on which is the male and female. If the female is the Nigerian Dwarf watch out for kidding problems. Other than that if they can physically reach each other it should be possible.
no
You can check its teeth as to how many adult teeth it has.
As a goat ages more of their front teeth will come in up until the age of 5. When the goat has all his/her teeth provided none have fallen out there should be 8 bottom teeth. Goats have a strong pad in the upper jaw instead of teeth. They do have some molars in the back of the upper jaw.