Answer:
1. Malvolio's love for Olivia is a one sided love, and it can be described as Malvolio desire for Olivia's money and power instead of true love. Malvolio always daydream about Oliva marrying him and him ordering Sir Toby around, as he thinks too highly of himself. However, Viola is dressed up and disguised as a man, and she was in love with Orsino, despite the fact that Orsino does not realise that Viola was actually a girl, Orsiono also loves Olivia and sent Viola to express his love to Olivia, which hurted Viola. In the end of the story, Orsino finally realizes that Viola is a girl and they fell in love.
2. Malvolio will fail because Olivia only treated him as his steward, Malvolio also thinks too highly of himself, which leads him into making foolish actions.