“Kudos” ends in s, so many people assume it is plural. Its history is different: English borrowed it as a singular noun meaning praise.

Deep seated is the standard phrase for something firmly established. Deep seeded is a common misspelling shaped by sound.

“None” can take a singular or plural verb. The best choice depends on whether you mean not one or not any.

The standard phrase is toe the line. It started with toes placed on a line, and now it means following rules or meeting a standard.

Groak names the act of staring at someone while they eat, hoping for food. It is an informal, playful word with a very clear image.