False. It is a simile. Both metaphors and similes are comparisons, but similes use like or as (like this one does), and metaphors don't.
True. This statement is an example of a metaphor because it compares the speaker's brother to a snail, suggesting that he is slow in the morning. To determine whether a statement is a metaphor, you should look for comparisons that do not use "like" or "as" to make the comparison, as those would indicate a simile instead.