In the British nobility, a viscount is ranked immediately above a baron and immediately below an earl. I doubt whether a viscount would "serve under an earl" as you put it.
earl
The French Vampire, Viscount de Morieve, lived during the French Revolution, if legend is correct, and for nearly a hundred years after that, before his grandson had him staked.
King, Prince, Duke, Marquess, Earl, Viscount, Baron.
No. The eldest son of an Earl usually takes on one of his father's lesser titles: for instance say the Earl of X also has the titles Viscount Y and Baron Z. The Earl's son is thus known as Viscount Y. If Viscount Y has a son in his father's lifetime, that son, the Earl's grandson becomes known as Baron Z. Note that these titles are courtesy titles, and are not official. The Earl of X's son may be known as Viscount Y, but the official Viscount Y is still the Earl himself. Note also that in some cases an Earl will not have any lesser subsidiary titles (i.e. the Earl Temple of Stowe). In such a case, the Earl's son and heir will be given a made-up title (the Earl Temple's son is known as Lord Langton, a title that does not legally exist). These same rules apply to Dukes and Marquesses, but not to Viscounts or Barons: sons of Viscounts and Barons are not entitled to courtesy titles.
Viscount Hill was created in 1727.
Viscount Exmouth was created in 1816.
Viscount Bangor was created in 1781.
Viscount Palmerston was created in 1723.
Viscount Scarsdale was created in 1636.
Viscount Doneraile was created in 1703.
Viscount of Primrose was created in 1703.
Viscount of Oxfuird was created in 1627.
Viscount Ridley was created in 1756.
Viscount Southwell was created in 1662.
Viscount Valentia was created in 1620.
The Viscount of Adrilankha was created in 2003.