novice questions about sedimentary and metamorphic rock formation

Just got back from a long trip through the southwest (from Atlanta). Wow!! Passed through Great Lakes on way back (Apostle Islands, Pictured Rocks Natl Lakeshore). Wow again! Anyway, I have a few questions and found this forum. I have no training in geology other than what I learned way back when in high school so these are very much novice questions. Here's one. I presume there is a great deal of variation from place to place but am wondering what the range might be for how many years are reflected in let's say an inch of sedimentary layers. In other words, if you're looking at the Grand Canyon for example, how many years passed to lay down 1 inch of sediment?

Also, how much overhead material is required to produce enough pressure to turn sand into sandstone, or to create schist or gneiss? For example, if you have a sand layer 200 ft under the surface, will that be enough pressure to create sandstone, or is 1/4 mile or many miles of material necessary?

And for metamorphic rock, is the necessary heat generated deep in the earth or can pressure generated heat be sufficient?

Thanks
Dave