First, "Sweet lips" is an endearing expression used to express someone's sexual desirability or romantic attractiveness. It is, generally, complimentary in a sexual way. Literally it means someone has lips that are sweet to the taste and enjoyable to kiss.
Second, the term sultry literally means "humid" or damp and may be used to refer to a woman's sexual desirability. Use of the term "sultry" with reference to a woman is generally restricted for reference to women who are more available sexually than most.
Third...I'll leave this one to the poets...