When someone becomes excited, their pupils can dilate to up to four times their original size. Conversely, an angry, negative mood causes the pupils to contract to what are commonly known as 'beady little eyes' or 'snake eyes'. Lighter eyes can look more attractive because it's easier to see the dilation taking place.
The term papilla (plural: papillae) generally means a nipple-like structure, and may refer to: Mammary papilla, or nipple. Amphibian papilla and basal papilla, part of the inner ear of the frog. Interdental papilla, part of the gingiva between teeth.
They are the vallate papillae, everyone has them toward the back of the tongue. They vary in number up to 12 in a V shape toward the back of the tongue. They vary in size from time to time in the same individual and this is within normal expectations. So it's understandable that others in your group might not (apparently) have them. They do actually have them though not easily visible at the moment.