Thurn and Taxis Christmas Market

No idea if it can sell out but it seems highly unlikely to me. There is a larger, more complete market in in the center of town that is for free.

We visited the Romantic Market once and enjoyed its atmosphere with small camp-like fires. We liked it but have not been tempted to go back during a couple more trips to Regensburg during Advent Season. It was not especially crowded when we were there.

Yes, buying your tickets in advance online means you get to skip the long line at the entrance.

We were there in December and bought online prior. I believe it was a little reduced in price and sped up entry. We went when it first opened and stayed until after dark. By the time we left it was quite crowded and there was a long line. We were glad we went early.

Thank you for the information!