Question

Most nouns ending in y preceded by a consonant form their plurals by changing the y to i and adding -es.

Answer 1

True

Most nouns that end with consonant+y change the y to i and add -es. For example, city-cities, baby-babies, duty-duties, secretary-secretaries. This is not true of words that end in vowel+y. These nouns often just add s. For example, valley-valleys, alley-alleys, monkey-monkeys.

There are many other rules about pluralizing nouns. Most words just add s for the plural form. Some others such as ss, ch, and others that are similar add and es to the word. In a few cases the verb doesn't change forms in their mouth.

Answer 2

True. Examples would be:
 fly to flies
Cry to cries
dry to dries
butterfly to butterflies