That functionality is on the TODO list that I haven't committed to disk yet. You can't specify the maximum number of threads to list. If you have many threads and a tall xterm, B will always try to display as many as it can fit. The size of most of the columns in the display has a small maximum width. I have no good idea as to how best to deal with that yet.
Suggestions are welcome.
Full query info is not implemented. I'd like to be able to show the whole query for a given thread. This will be especially useful in tracking slow queries. Contact me for details. Add a feature.