Yes, you can use the TrueTech 4000 (TT4000) to apply Boracare. Be sure to still mix the BoraCare in a separate container first, and the pour the finished solution into your sprayer tank. This sprayer comes with a 25 foot hose, but there is a 50 foot dual hose available, if you need the extra reach. The manufacturer suggests using the 8002 tip that comes with the sprayer for applying Boracare.
Yes, you can purchase 50' hoses for the TrueTech 4000 4 in 1 Portable Applicator with Compressor, and no adding these would not affect the pressure of the unit, per the manufacturer.