Do all the available hurricane names get used during a season?

Answer 1

Only once (2005) has the number of storms exceeded the 21 names on the list. The list was set at 21 due to the previous maximum set in 1933 in the North Atlantic. Since the storm naming list was established in 1953 the closest before 2005 was 19 storms in 1988 and 1995.

Answer 2

Only if there are 21 names on the Atlantic Hurricane list. So if there's at least 21 storms then those names will be used. If there are more than 21 storms than the resort to the Greek Alphabet. This happended in 2005. They used all their names and the used the letters alpha, beta, gamma, delta, epsilon and zeta. Here's the Greek Alphabet for future references.

Alpha
Beta
Gamma
Delta
Epsilon
Zeta
Eta
Theta
Iota
Kappa
Lambda
Mu
Nu
Xi
Omicron
Pi
Rho
Sigma
Tau
Upsilon
Phi
Chi
Psi
Omega

Answer 3

Not usually. But when all the available names get used up, if there are still more hurricanes they get named after letters in the Greek alphabet. That happened in 2005. Below is the 2005 hurricane name list.

Arlene
Bret
Cindy
Dennis
Emily
Franklin
Gert
Harvey
Irene
Jose
Katrina
Lee
Maria
Nate
Ophelia
Philippe
Rita
Stan
Tammy
Vince
Wilma

Alpha
Beta
Gamma
Delta
Epsilon
Zeta

http://geography.about.com/od/physicalgeography/a/2005names.htm