You could say imperative in a more formal situation. More on reddit.com

They are not all exactly the same, no. Crucial and Indispensable mean something that you can't do without, so they are stronger than just important. They also have slightly different collocations and connotations, so we tend to use them in different contexts. Indispensable is usually applied to people or objects, whereas crucial tends to be applied more broadly, including to more abstract things like ideas or events. Note that these are both only tendencies, though. Anything that is absolutely needed can be described with either word. Prominent is the least similar. It literally means something that sticks out, like a chimney from a roof. Metaphorically, and more commonly, it means something that is noticeable, often because it is important. It's frequently used for important people, like "a prominent member of the community" or "a prominent businessman". More on reddit.com

"an opinion based on experience " That's "expertise". For searching for synonyms I use thesaurus.com (I know some people dislike this website though), and put in whatever the first word in my stream of conscious is for what I'm looking for, for example, if I'm trying to remember the word omen, I might try "voodoo" or "forboding", then click through the results and see if anything triggers my memory/reminds me what the word which on the tip of my tongue is, the word I'm looking for may be the first result anyway. If you have another thesaurus website you prefer then use that instead. More on reddit.com

You don't need to say "in this essay I will go over --" or "... you will see/learn" just say the facts. "Cats have fur and have four legs and are also found in many North American homes. They also hunt, require low energy, and can be trained to go to the bathroom in a box. While some people see dogs as superior pets, cats are the most lovable and efficient domesticated animal a family can purchase." Then go into into the reasons you listed, like hunting and energy. Convince them without telling them they need to be convinced. More on reddit.com