1)
Why did she say to the messengers "your Amah"?
1.
Ralbag: Amidst humility, she said that it would suffice to marry one of David's servants, and wash [that man's] feet, like a woman does for her husband. 1
2.
Malbim: One's Shali'ach is like himself (it is as if she speaks to David).
1
Why did she say "Avdei (plural) Adoni"? (PF)
2)
Why did she call herself a Shifchah?
1.
Metzudas David: It is as if she is not worthy to marry David, only to be a slave, to wash the feet of his servants.