I noticed the selection of animals during embark does not include any or most of the default Dwarf Fortress animals. Is this by design or am I missing something. I want to bring cats for example...
It's by design. You have a new set of pets to choose from, like Bronze Centurions, Batwings, Utility Spiders and the like. If you want classic cat-like action, buy batwings. If you just want something that cleans your fortress without adopting anyone, Utility Spiders are the way to go.
cant tell by OP, which races are playable?
Dwarves on Fortress Mode.
As for Adventurer Mode, you can choose any race save the Void Dwellers. There are also "Outsider Classes" to choose from, such as Barbarians, Magicians, Necromancers, Treasure Hunters and Vagabonds.
Barbarians - They have an ability that makes them immune to pain and boosts their ability to hit an enemy. They have enhanced combat learning rates.
Magicians - They have flame-oriented spells by default. They have default learning rates.
Necromancers - They can raise the dead. Note that it doesn't make you immune to being targeted by the dead until you read a slab that confers immortality or become a vampire.
Treasure Hunters - They do not have any special abilities, but they learn all skills 5x faster than anyone.
Vagabonds - They have a high skill in ambusher, dodging and knife-user. They also have a skill that enhances their speed and makes them immune to paralysis for a time.