As with Jennifer ...
Of course I'm a Primary teacher so the expectstions for self-control are not as high!
But with Primary children and older children I will encourage them to use the toilets at break times, have a quiet word with the child who needs to go 5 mins after the beginning of every class (in other words, once they've sat still for long enough for the need to register) ... but I would never ever deny a child from going at all ... I don't want a mess to clear up!
I encourage questions ... there may be times when you ask them to let you finish a presentation or explanation first, or discuss things with their partners/table groups first, but in most cases hearing their comments and questions is the main way that you understand how they are thinking and what their understanding actually is .....
You sound to have had some awful experiences with teachers, WriterWoman, I do hope that you meet some good ones soon!
Helen