The below example may be helpful for 1st question..
1. As your brother, I must warn you to be careful(iam your brother)
2. Like your brother, I must warn you to be careful(iam not your brother, but he and I have similar attitudes)
>>>> humingbirds (like/as) insects
1. As your brother, I must warn you to be careful(iam your brother)
2. Like your brother, I must warn you to be careful(iam not your brother, but he and I have similar attitudes)
>>>> humingbirds (like/as) insects
