I'd been so looking forward to sharing my news, dropping it at her feet like a dog retrieving a game bird peppered with shot.
What does "dropping it at her feet" mean?
Presenting/offering it to her.
2) What does "Creeping dread" mean "I heard her voice, creeping dread"? Does it mean "creepy and scary"?
Creeping probably refers to the dread becoming stronger with time. It arrives then grows.
3) Is "wee skank" stronger or weaker than "skank"?
"wee" usually means small. (not smaller) Might need more context for this example.
4) Do you use "She got caught stealing" or "She got caught purloining" more often?
"purloin" & "purloining" are virtually never heard in normal speech. Known by all, but less used.
Generally purloining would be transitive, I think. Hence purloining
5) What does "the jagged edge in her voice hardening" mean? I know the shape of jagged edge, but I don't know what "hardening" mean here.
Became sharper, more obvious, more threatening, (possibly, depending on context, became less likely to care, more insulated from feeling, less sympathetic).