baticks have been boiled to remove the wax so they are not likely to shrink any more that they already have. As the previous poster said they also tend to be quite closely woven so the only wash or not ot wash dilema results from potentail bleeding of dye.
Pre test everything or just wash everything. Clipping off the corners reduces the ammount of catching of the fraying.
I also know someone who used to do that so she could tell if a fabric in her stash had been washed! Corners off washed already corners intact not yet washed.
Have fun sound like a lovely project.
becks