Store SO SKU #
A: I used #10 wood screws for mine.
A: I use Simpson #9 x 1-1/2" SD Connector Screws. They are galvanized and exterior grade. They can usually be found in the store immediately adjacent to the gusset angles.
A: If you intend to use this to create a floating seat then no, it will not work. If you want to use this to support the seat so it is "hanging" on the connector then, yes it will work. The strength really comes down to the screws in this case and if they havea good "bite" in the lumber.
A: It should carry the loads without any problem. Would recommend a deck-type screw or wood screw; not a drywall screw.
A: Install with 10d common nails or #9 x 1-1/2 in. Strong-Drive SD screws
A: I used Simpson 10d 1-1/2" hot-dip galvanized deck nails without any problems
A: If they are stainless steel you can not paint them. If they are galvanized, you need to wipe off the coating with a good strong cleaner to remove the coating. After that put a good brand of spray primer (I used Rust-Oleum) and paint the color of your choice. You need to have a good adhesion of the primer so the paint does not peel off. Simpson also has brackets that are pre-painted but those are more likely a special order. Good Luck
A: Yes, they are paintable, I painted mine with water base outside paint and it has held up extremely well now for two years. As for the weight capacity, that is very difficult to assign especially in the context for which I imagine you to be considering using this bracket. For one thing the type and length of fastener as well as the type and condition of the material of the planter box and seating material might cause the fasteners to pull out of the material and cause a failure before the bracket itself were to deform and fail. And what weight are you anticipating and how far would that weight be positioned from the edge of the seat where the gusset angle is fastened? All of these undefined variables make it impossible to assign a weight capacity. All that said, using these brackets at the rear of a seating bench with no other support seems like a misapplication of these brackets. They are intended to attach two members but not to use in the application that I imagine you are considering.
A: Yes these are paintable, as long as you prepare the surface properly making sure it is free of dirt and oil. Weight capacity is about 500lbs if properly installed. Please see page six (6) of https://www.icc-es.org/wp-content/uploads/report-directory/ESR-3096.pdf for allowable load installation.