Yes, the Chapin Industrial Poly Bleach 1 Gallon Sprayer can be used with hydrogen peroxide according to the manufacturer. The spray nozzle does not have a fine mist setting. It is just a basic nozzle cap that does a stream spray.
Yes, the Chapin Industrial Poly Bleach Sprayer 1 Gal. (20075) can be used with herbicides such as 2,4-D.
Chapin does offer a longer wand assembly here and a fan shaped nozzle kit here that is compatible with the Chapin Industrial Poly Bleach Sprayer 1 Gal. (20075) sprayer.