Yes majority of Tamils are Hindu's and a considerable number Christians, Sri Lankan Muslims are divided in to two distinct groups Moors and Malays
And within that The Moors, Consists of descendants from the Arab peninsular and North Africa settled through thousands of years married to local women and then you get the Eastern (Tamil) Muslims who were brought in by the Dutch colonists as indentured labor from South India mainly Tamil Nadu, Andra (Coromandel Coast) and Kerala (Malabar Coast) in the 17th century.. They are settled mainly in the Eastern and Northern provinces and Colombo, Moors of Arab descent live across the island mainly out side the North East.. Eastern(Tamil) Muslims consider Tamil as their mother tongue, While other Moors are multi lingual
Malays are a distinct ethnic group originating from the Malay peninsular and Java South East Asia, With their own culture and Language (Bhasa Malayu)
About the visa issue, Yeah from what i gathered it had to do with Drug smuggling and illegal immigration.. Lets hope things improve so that Pakistanis will get to travel without hindrance