The webpage on Wikipedia says it has taken the list from Forbes … but when you check the actaul list of Forbes, Mansha is not there on 99 …infact you can make it out that it is a hoax because there is more than one entry for 98 so technically there cannot be any 99 !!! As regards to him and the others being billionaries, it is possible that they are but they haven’t been identified by Forbes.
As regards to number of Indians in teh lsit … Wikipedia give the reference of March 2009 list, which had 21 … but teh new list give a total of 52 … here is the latest list …
India’s Richest - Forbes.com