Measure the water into a glass measuring cup and add the yeast. Stir to dissolve and let it stand for 5 minutes.
Heat the milk in the microwave and pour it into a large mixer bowl. Add the oil, sugar, and salt. Mix in 1 cup of flour. Add the eggs and beat again. Stir in the yeast mixture. Adding 1 cup at a time, stir in 4 more cups of flour. Add enough remaining flour to make a soft dough.
Turn the dough onto a floured surface and knead gently until the dough is smooth and elastic. Cover and let rest while you wash the mixing bowl.
Lightly grease the mixing bowl and put the dough in the bowl, turning once. Spray plastic wrap with cooking spray and cover the bowl. Let rise in a warm place until the dough is doubled in bulk. 1 to 1 1/2 hours. Grease a 12 x 18 inch sheet pan and set aside.
Punch down the dough. Roll out the dough on a floured surface into a large rectangle, about 20 x 14 inches or larger. Mix the butter, 1/2 cup sugar, and grated peel together. Spread onto the dough before rolling up. Starting on one long side, roll up the dough into a tightly rolled log.
Mark the center of the roll with a knife mark and then make nine evenly spaced marks on each side of center, marking off a total of 20 rolls. Slice with a strand of heavy-duty thread or dental floss: place the thread under the dough, crisscross it over the dough, and pull quickly to make a clean cut for each roll. Place the rolls in the prepared pans.
Cover the filled pans with dish towels and let rise again until nearly double, about 30 minutes. Meanwhile, preheat the oven to 400 degrees. When the rolls have risen, bake 10-15 minutes, until just lightly browned.
Make the frosting and frost the rolls in the pan while still warm. Serve right away. Freeze cooled rolls in resealable plastic freezer bags.