You can install as many animations as you want. 1, 2, 30, that's up to you.
If you're new to The Sims, playing a scenario would be a way of learning the ropes of the game.
If you choose to start playing a new game without a scenario, all you have to do is create your sim (or sims if you want to start with a family) and play the tutorial to learn the hang of it.
The packs in the main menu are ads of DLCs for the game. There are 4 types of it:
- Expansion Packs: they add a lot of new functionalities to your game. A new gameplay, new missions to accomplish, new activities, new clothes, furniture and even new cities.
- Game Packs: They add new functionalities to your game but in a smaller scale when compared to Expansion Packs. They're mostly focused on gameplay so you'll get not just new clothes, furniture, etc, but also something brand new to explore. IE Vampires, Werewolves, Spas, Restaurants, Vacations...
- Stuff Packs: Much smaller than a Game Pack. They add some new clothes and furniture, and usually come with an object that has unique features and won't be found in any other pack. IE: a séance table, a climbing wall, a chocolate fountain, a vanity...
- Kits: the smallest of packs, they add something very specific. Each kit comes with something thematic, such as "build a Moroccan house", or "dress like the 90s"
