just place a bowl on the scale and zero it out (mine I just hit the on button again) the scale will read zero and you can add your hops to the bowl to weight them. This is how I weight grains I'm guessing you don't use grain yet?
For clean up just use a large mesh bag to hold the hops (like the ones poeple use for BIAB mashes) they cost about $2 and are reusable. Pull it out when done and discard the hops. You will want to dunk it up and down a every few minutes during your boil as well to make sure the wort is getting inside.
But pellet hops are probably just easier. I always use a hop bag, the one time I didn't I ended up with a hop leaf in nearly every glass.
P1: Mild Porter P2: Empty P3: Empty
Keg 1: Saison Keg 2: Empty Keg 3: Empty