I would be curious what other people think about this.
We have all heard it [or done it] before in a seminar.
"I have three questions. The first is, ..[long and technical].... The second is, . [longer..].. The third is..."
I think in seminars audience members should ask only one question at a time. I think it is hard for the speaker to keep track of the questions and answer them all in a coherent and succinct manner.
It is a good discipline for us to try and focus our questions down to one key issue and to try and ask ones that will be helpful to most people present.