Batch Sparge Question

I've searched the threads and have read several articles and still have two simple questions:

1. In a two step batch sparge process I first add sparge water, equal to mash tun dead space, to mash, stir, recirculate, and drain to kettle. Second step involves adding equal amount of sparge water to first running, to make up whole of total preboil volumes as calculated by BS. Question: How long do I let sparge water rest in mash tun?  In my research it seems I pour in sparge water stir, recirculate, and drain. I believe I should be thinking of the process as rinsing and not steeping, that process was already performed during the mash. Tell me I answered my own question.

2. BS says my sparge water should be 168ºF (< 170ºF decrease tannin extraction). Question: Is it the sparge water or the total of grain and sparge water in mash tun to be at 168ºF?

Thanks for clarification....trying to tune in my equipment and brew process.

Yes, fill, stir, let rest a minute?, and then drain.  Conversion is done; you're are merely rinsing. 

Yes, use hotter water, so that the refilled MLT with grains hits 168F, for maximum rinsing power. 

Thanks for the confirmation.