In the USA a prospective employer can ask whatever they want of previous employers, but they can only expect get answers to three questions because of potential legal liability reasons:
Concern about lawsuits is why most employers only confirm dates of employment, your position.
- did you work there, if so
- how long
and
- what was your title.
These are all verifiable, objective and fact based.
Anything else that could be subjective or used to keep you from getting the job your former employers will refuse to answer, so that you can't sue the previous employer for keeping you from getting the job.
This goes for current co-workers as well, they will be forbidden from giving any kind of reference ( positive or negative ) for you.
All that said, defamation lawsuits like these are usually very hard to
prove and the burden is 100% on the claimant. But most companies would
just rather save the time and money in not having to defend themselves
by refusing to put themselves in a position they had to defend to
begin with.
These questions are not that strange, they probably are being used to set what is called a anchor point to gauge how much they can low ball you for. In this case you can exaggerate how little you paid for healthcare and how much you were paid, and how generous your bonuses were; they can't prove or disprove any of this information.
The buyer uses the lowball tactic to start the negotiation with an
exceptionally low offer. They do so in an effort to set the anchor
point in their favor, whereby creating the tone for the negotiation.
You can validate your bid by explaining why it is so low.
Be careful to do your research beforehand so that you are aware of
what the true market value is for the product, or service, you are
seeking to buy. If you do not, and you offer is insultingly low, the
seller may walk away from the transaction without further negotiation.
An extremely low offer can possibly damage trust and hinder future
negotiations.
Here the buyer is the employer and the seller and the product is you.