You may be able to get 10-16% interest. The lien is usually in first position because liens from property tax have seniority.
You can buy around the country. Each county has their own procedure. Check the county web sites.
If you're interested in a property, maybe a local realtor will snap some pictures and send them to you for a commitment to list with them if you sell.
Most liens do not result in you owning the property. But you will get your interest from paying off the property tax. On some occasions you will get the deed.
I think the key is volume buying. There are websites and seminars for how to do this. I suggest you attend one of them.
Best wishes.
I'm unclear about the interest. How do I earn interest by paying off the tax?