I sort out the Zn and throw the rest into the pot. Fe will float to the top with the clips and get strained out. About 80% of my WW's are clip on and the rest stick on, which are pure lead or very close to. Shooting 45 and 357 I've never had a problem going up to a 50/50 mix, always hardcast into a bucket of water. I recommend a wire egg strainer for the clips.
Once I have them sorted should I melt and pour ingots of straight up WW or should I mix any pure lead in with them?
Are you melting them in a different pot than what you are casting them from? Seems simpler to just melt it once and turn it into bullets.