I am not a lawyer, I am not your lawyer, etc. Also, there are big differences in how everything goes down in a particular case. That being said…
To clarify, you’re a creditor of the Debtor, and you have a lien on some of his property that’s now being sold by a Trustee? Assuming its a Chapter 7, you are a creditor, and in a way, the Trustee is actually working for you, so it’s okay to call him if you need to.
“Free and clear of liens” generally means that the liens, if not paid in full by the sale, will not continue to be attached to the property, but will dealt with further in the bankruptcy. Have you filed a claim in the bankruptcy?
Upon a sale, creditors are paid in the order of priority, which means different things in different situations. For real estate, at closing, liens are paid as follows: closing costs/broker fees, real estate taxes, mortgages, everyone else in order of their lien being recorded. You say you bought a tax lien, meaning that you bought the right to collect the lien, like a tax certificate investment? If so, you should come in order not of real estate taxes (those were “paid” when you bought the tax cert) but at the everyone else level. This however can vary according to state law.
So, in a bankruptcy, everything would proceed as in a regular sale, and anyone who doesn’t get paid in full now has an unsecured claim in the bankruptcy. Once all the assets are sold/liquidated, the Trustee then pays claim of the Estate in the order of priority - administrative bankruptcy claims, any unpaid secured creditors (remember - you’d be unsecured at this point), priority claims like income taxes and child support arrears, and then unsecureds. Each tier gets paid in full before the next one gets any money, and if there’s not enough to go around for that tier, then everyone in the tier shares pro rata based on their claim amount.
I was a Trustee paralegal for 15 years, but remember this is worth what you paid for it. 