Misc: What is the second most frequently used letter in the English language?

Questions

Which artist, remembered more for his portraits than his landscapes, was born in Sudbury, Suffolk, in 1717?

The Mason-Dixon line ran between Maryland and which other American State?

Which American president renamed "Shangri-la" as "Camp David" after his grandson?

Which band comprises sisters Andrea, Sharon, and Caroline with their brother Jim?

Which island is known to its inhabitants as Kerkyra?