School play Lumix G5 + 45-150 zoom + pany / Leica 1.4 for snaps afterwards - need advice

So I was wondering how to set up the camera? I think min speed might be wise so er.. 30? (I wonder if I can set a 'go no lower than xxx')

Then what? F4 or F5.6 is pretty dark - I dont mind a bit of grain as long as I get the shot

Is there an auto ISO setting? I suppose I might use that and keep it at the widest apertures possible?

I wil be quite far from the stage - I imagine my focus assist light will

a) be useless at distance?

and

b) annoy people?

Bright red focus assist from the audience is annoying right? Disruptive to the performance?

Should have gone to dress rehearsal but had a work thing.. OH well, in a the deep end with the new toys..

Wanted to take a mono pod.. but didn't get the chance to go buy one..

Thanks