I don't think Nesta is an African name... or actually it probably is given the amount of cultures and names in Africa, but I think Bob's biological dad gave him that name. My grandparents on my dad's side live on Nesta Road in Cardiff, Wales, so I would suspect its a Welsh/Celtic name.
There are many books and websites that list African names and their meanings. I'm not really sure what you mean by Rastafari names. That could mean generally African, specifically Amharic, Biblical, Khemetic, or named after Rastafari people...
Personally when I have youths I'll lean towards Nyabinghi for my first daughter, Nya for short, Makkonen for my first son, Makko for short (that's my cousin's name and I like it, sounds strong yunno, who would wanna mess with MAKKO?) Of course it won't be only my decision...
FAIR USE NOTICE:
This site may at times contain copyrighted material the use of which has not always been specifically authorized by the copyright owner. We are making such material available in our efforts to advance understanding of environmental, political, human rights, economic, democracy, scientific, and social justice issues, etc. We believe this constitutes a 'fair use' of any such copyrighted material as provided for in section 107 of the US Copyright Law. If you wish to use copyrighted material from this site for purposes of your own that go beyond 'fair use', you must obtain permission from the copyright owner.
For more information go to: http://www.law.cornell.edu/uscode/17/107.shtml