Your UDOR Pump is NOT "specially designed" for roof cleaning, I am sorry to say. I have one in my shed that quit on me, years ago. You are welcome to drive here to see it. The UDOR is a pump for pest control, tree and agricultural spraying, etc. The crooks at UDOR, who refused to honor my warranty on their UDOR Zeta Pump when it broke, got the bright idea to market the pump to our roof cleaning industry.
All you have to do is look at what materials are used in it, to know there are much better materials to make a pump from.
Nevertheless, it will last awhile, as long as you rinse it out RIGHT AWAY. The Diaphragms last awhile, Doubt you will need to worry about them.
Glad you got new fittings made out of Polyproplyne !
Your old ones were NYLON, a big No NO for roof cleaning chemical use.
Next, you either need a new tank, or move the bypass hose to the TOP of the tank.
That Skid you bought looks like it was aimed at the Pest Control People. They seldom if ever fill their tanks all the way up, so a pump bypass on the side of the tank is no big deal.