Baby Yoda is introduced to the series in the first episode when the main character the Mandalorian claims a large bounty and finds baby yoda who was the target. He decides to not to claim the bounty and keep Grogu. The reason Grogu is so valuable is because his species is extremely strong with thte force.
He is not Yoda from the origional Star Wars movies but is he is the same species. His decision leads to adventures that you go through in an action packed show.
No, baby yoda is of the same species but are completely different people. The species is very strong with the force which is why they are both so valuable.
In the mandalorian he is never actually refered to as baby yoda as this is a fan name. In the show he is called the child at first and then as time goes on the audience finds out his name is Grogu
Baby Yoda still remains roughly unkown but has been has done things that only sith have done. He hasn't been around long enough to say if he is good or evil.