Sounds good but I would be careful about using sand. Fine sand such as playground sand, or beach sand has occasionally impacted a chicken's crop causing its death. If you are going to use sand, use a course and sharp river sand that is rough,with different sized pebbles in it. You should be able to find this type of sand at a local sand & gravel yard where they have it washed it. For attaching the hardware cloth I have always used galvanized fence staples and never had a problem with them, although some people claim that drywall screws and washers will make it more predator proof. Tin snips, diagonal cutters, or heavy shears all work well for cutting hardward cloth, or if you have one and can take good measurements, a table or circular saw will also work well and is much faster.