One more thing, sparging at 164 is fine too. Think about it, most boil in a bag brewers don't spare at all. As long as you got as much out of the grains as you can, you are doing it right.
151 is fine. I've done that a bunch. 155 would have given you a few more fermentable sugars, but it is still going to taste great.
The leftover wort is great for a starter for next time. Freeze it in water bottles and boil it when you want to make a yeast starter.
Your batch will be perfect...
Weizenbock. I did this a month ago. The repitched yeast from an Imperial Hefeweizen(1.072) goes pretty crazy, but makes a fabulous Weizenbock(1.075). Blow off tube is a must and you will probably clean it out a few times. Good luck.