According to the manufacturer, the shelf life for the Southern Ag 20-20-20 Soluble Fertilizer is indefinite as long as the product stays at room temperature with no humidity or moisture.
Yes, Southern Ag 20-20-20 Soluble Fertilizer can be used with a sprayer.
There should not be any reason that you could not apply them at the same time. We always suggest a jar test first when tank mixing.
The Southern Ag 20-20-20 Soluble Fertilizer can be used on edibles, including orange trees, as well as vegetables, turf and ornamentals.
Southern Ag 20-20-20 Soluble Fertilizer can be applied as a spray or a drench, depending on your specific application purposes.
We really can't advise you on using Southern Ag 20-20-20 fertilizer as it is not labeled for orchids specifically.