The plains style bows I've made with ash (two) were made from boards....and since they were backed I wasn't too concerned about the grain. They turned out OK but the ash I was using seemed weak in compression and most of the handle reflex pulled out during the tillering.......it may have been the humid weather. The ash also seemed to be quite a bit less flexible than the juniper and elm I was using (for other plains bows) during the same time period.
As far as staves....I think the bark can be peeled off and you're done. I had a large piece of ash (18" diameter) but I was only 43" long so I didn't make any bows out of it....but the bark came off easily.
It's been said that ash and sinew is a good combination but, in my experience, juniper or mulberry seem to be better choices for sinew backing. Soon, I will try backing a mesquite bow (that is shaped and drying) and, so far, seems like a good choice for sinew backing as well.