While this seems rather unintuitive, since Overkill will kill the creature you target, this wont cause Jaws of Defeats trigger to fizzle
If the symbol is black, the card is common
It will be only an Insect, not any other creature types
When I started cataloging my Magic collection, I started with my Black section (the smallest), and quickly discovered that if I was to have a complete catalog, I had to list all the sets that my cards were from, as well as the number of each card I had, the condition it was in, etc
Some careful deckbuilding is needed, but tutoring for a one-drop creature, enchantment or artifact is an incredibly flexible ability, and can generally find the perfect silver bullet so long as you include it
For example, as Emet-Selch's last ability resolves, you have the option to transform it