GENERAL KNOWLEDGE: Who appears on the 100,000 dollar (US) note?

Questions

what is the largest asteroid that has been observed?

comet that slammed into jupiter, in the mid 1990s, that reportedly would have destroyed all semblance of life on earth?

comet which visited in 1998, prompting a doomsday cult of about 30 people to commit suicide.?

name of the saturn probe launched in 1998, amid controversy over its nuclear fuel?

what does wysiwyg stand for?