are your responsibility -- not the broker's, unless the broker is not a "broker" but is a "dealer" (a dealer is a state-registered reseller who buys and resells title and is
therefore the seller -- whereas a broker is an agent for the seller, who is usually a third-party who has title).
If she's worried about disclosure just tell her to give you a letter of understanding that the taxes are not included in the selling price, and you can counter-sign that.
Anything more just muddies the clarity of your contract -- you only want ONE agreement, and anything else must be an addendum to that one document, not a separate agreement.
You don't HAVE to sign anything you're not comfortable with and you should not sign anything that has unclear implications.
As for "fees" usually brokers fees are paid by the seller, and come out of the purchase price. If there are any other fees (yard fees, etc.) those should be stipulated in detail -- as those are usually born by the seller.
Only fees associated with your own survey and sea trial should be paid by you.
You should NOT agree to undisclosed fees and you should not allow yourself to be pressured. He who holds the buck$ is KING, and you should walk if they don't respect that.
BTW - I'm not an attorney (just a businessman) so take my advice as "practical advice" not legal