I have done two very similar brews to the one you are planning and they turned out great.
The first one i grated the sweet potato and i ended up with a stuck mash.....a very bad stuck mash...the beer however turned out great. I used 04 yeast.
The second brew i sliced the potato into thin...
These are the established hops in South Africa
http://www.hopsteiner.com/varieties/southafrica.php
there are a few very yummy experimental ones on trial in the local market which have some interesting flavors.