1) how well should I trust the strike temps beersmith gives me?
If you've given it all the correct inputs (grain temp, volume, equipment) It should put you dead on
2)it gives me 3 batch sparge steps. should I just pour these in and wait for the wort to stop draining and then pour in the next volume of batch sparge water and repeat?
I normally do two batch sparges. Take half of your needed sparge water, pout it in and stir the crap out of it, drain and repeat.
3) should I stir the mash?
When you dough in you should stir very well to make sure all your grain is saturated and that you don't have dough balls. This should also equalize the temp across the grain bed. After the dough in I sometimes give it a good stir at 30 minutes to check temp, but I'm starting to realize this isn't necessary.
4) how quickly should I pour in the initial water?
Just dump it in
5) how quickly should I pour in the sparge water?
6) any further advice for a first time all grain brewer?
Have a quart of boiling water on standby just in case you miss your temp low. Take good notes and make sure you know how much your system will boil off so you can hit the proper volume. Ensure you Vorlauf! (SP)