Of course the students are going to make lots of mistakes, but, they need to practice, you have to correct them in a natural way without make them feel unconfortable
Of course not all the students are going to particpate, but at least they listen, most of the time we have to give them enough time for the income and when they feel able they would do, just give them time
If the students aren´t interested on the topic, then change it, for something they like.
Of course the students would feel more interested in speaking in their own mother tongue, because it´s too difficult, just let them try and if you listen them speking in their own tongue just ask them to speak in english