Yes smooth and sturdy
This birch is domestic, it is not imported
All of our PureBond panels are made in North America. We can offer a B-2 grade as a special order through the Prodesk at your local Home Depot if it is a store that we service. See the prodesk associate for details, or call 800-637-1609 if you have any additional questions.
No the edge is not strong enough because of the plies.
I did not see open knotholes on mine. It was ugly but no holes.
OK, so to find out the price you have to call them on the phone at online order assistance. The page your looking at that this question goes to is old they have made up a new product page for this product, the new internet number is 100092485 the new product page is located here https://www.homedepot.com/p/Columbia-Forest-Products-1-4-in-x-4-ft-x-8-ft-PureBond-Birch-Plywood-165891/100092485 The price is $27.72
IMHO, it depends on how much humidity it is exposed to. If it is a screened-in patio you probably want exterior grade plywood. My recommendation is to use plenty of nails/screws and an exterior grade paint.
Hi, when you say the top surface, I hope you do not mean the only top surface as this is only 1/4 inch thick. this wood is hard and smooth yet flexible enough to work for a surface that may have bends in it. but it is not going to be great at load bearing at this thickness so you would need more then 1 layer. as far as outside use goes, it would have to be sealed vary well and still should be protected from rain and snow if you want it to last a long time.