2. Lots of people are unlikeable. Who said Anakin had to be likeable? Indeed, it's more believable to have a flawed character fall from grace than someone who is purer than pure.
Likeable & flawed & eventually evil can be part of a character, as that is where Lucas missed the boat with Anakin. You have to have the audience atleast care for the characters, or they are not going to give a shit about him when he goes bad.
You look at any Mob Movie, and all the characters are evil and do awful things, but there is a charm about them that the audience gravitates to. Goodfellas is a perfect example where I like the main characters (Robert Deniro, Ray Liotta, and Joe Pesci), but they are essentially all bad people, who do bad things, and eventually pay for their sins at the end of the movie the same way Anakin did. Tony Soprano is another example of a person that is a flawed person, that does horrible things, yet the audience deep down likes him, and that is why you come back to watch the Soprano's each week for 6 seasons.
Lucas never made Anakin likeable in Episode 2 when he was played by Hayden Christenson. He didn't do anything bad until the Tusken slaughter, so he still had a good chunk of the movie for people to care about him. Many would argue Anakin should have been the same actor for 3 movies, so the audience could get to know him even more, but thats another argument.
The bottom line is that no matter whether a character is portrayed on screen as a good guy or bad guy, if the audience doesn't care about them, then why should we care about his ultimate demise?