Hi Will!
The word "KAMUSTA or KUMUSTA" comes from the Spanish phrase ¿Cómo está?
The standard Tagalog spelling is Kumusta, but most Filipinos now use Kamusta.
Kamusta ka? How are you? (for friends, same age or younger than you)
Kamusta na po kayo? How are you? (polite version for older people)
Hope it helps =)