"She would have loved this" "Would have she?"
"It would have worked!" "Would have it, now?"
Does it make any sense? Is there a grammar to follow for these cases?
The correct versions are:
These are grammatically similar to question tags.
The rules to follow have been covered previously ( When to use Does and Is while starting the Interrogative sentence? ). To clarify, though, where it's a verb phrase or multiple-auxiliary phrase ("would have"), you only include the first auxiliary verb in the inversion. You can't move a non-finite verb (such as "have" in "would have") to the start of the sentence.
Thus, "would she have?" and "would it have, now?" are correct.
Interestingly, if the auxiliary is part of a negative contraction, you can include the entire contraction in the inversion: "she wouldn't have" --> "wouldn't she have?".
(As the non-contracted question, "would she not have" is much more usual, although "would not she have" is also sometimes found.)