It's possible, yes, but be sure you have everything secure and build to local codes.
There's too many unknowns to determine if this will work, but the fact the post is square shouldn't change anything.
Depends on how you attached them and how wet they are at installation. It's possible.
Store can make cuts.
Thank you Bill for your recent inquiry for 6 in. x 6 in. x 16 ft. #2 Pressure-Treated Timber with The Home Depot. This item is not available in stores for pick up or online to ship. We currently do not have an ETA for when this will be back in stock. We appreciate your business and look forward to serving you in the future.
Hi Ellie, it looks like that this Timber is a store exclusive item and only able to be bought in a Home Depot store. Unfortunately we do not sell it with online stock for purchase. If you are unable to see the store inventory or price it is most likely either not a stocked item in your area or no longer available for purchase from Homedepot.com. I would advise you visit or contact your local Home Depot store for pricing and availability. Often they can provide a suitable alternative. Please follow the steps below to localize your Homedepot.com: 1. Localize Homedepot.com using your zip code (My Store Location: Change) 2. Choose the store where you want to pick up the item (Make this my Store) We appreciate your business and look forward to serving you in the future. Thank you for shopping Home Depot!
It is highly likely that what is in your local store is actually treated to ground contact.
Hi James. Thank you for your question. This product is not available in all our stores. I checked our Atlanta stores and it is available for $39.98. Please let us know if we can be of further assistance. Rick_HD_OC