There is no issue with eating basil according to kashrut (Jewish dietary law) as it is an herb that is easily washed.
Yes, basil is kosher.
Hindus do not eat beef no matter if it is Kosher or non-kosher.
Kosher is not a person, so it can't eat anything. But the blood of mammals and birds is not kosher, so people who keep kosher can't eat it.
people that are aligerick to basil
No, but halal-keeping people can eat kosher food, except for anything containing alcohol.
No, shell fish such as prawns are not kosher.
They eat it.
They eat any kind of meat except for pork. However, it MUST be kosher.
if it's kosher
for seasoning dishes
Kosher refers to food that is prepared according to the laws of kashrut. The people who keep kosher are Jews. Kosher is a classification, not a people. That being said, if the nachos and salsa are certified kosher, religious Jews who keep kosher can eat them.
Jews who keep kosher do not eat prawn, since it's not a kosher species of sea creature.