You have been given about the best advice you cold get,
1) look the clip on's over really well when separating them for zincers, then use a thermometer when you melt them and keep your temp lower than 725. Any remaining zincers and steel weights will float on the top with the clips, pull them out and toss them. I usually will keep mine around 650'ish from melt to ingots just to be sure.
2) flux with sawdust and you will be ahead of the game. Any type of hardwood from pine on up will work fine. Steer away from treated as the burning chemicals aren't so good for you to snort up if down wind. After your alloy is melted simply toss a handfull across the top, and let it carbonize, then stir it all up really well.
3)The mix is usually 50/50 for most WW / SO alloys but 75/25 will work out just as well for your purposed use. As mentioned a little tin might be in order once you get to pouring and see how they fill out. You only need to add as much is necessary for good fill out, and your set.
4) Congrats on the haul. A bucket of WW around my area would be akin to finding a winning scratch off in the parking lot of the store. It might happen, but the odds are better at hitting the power ball.
Lastly as mentioned, if you have any questions or need assistance head over to Castboolits, and by all means head over and download or print out this excellent free informational writeup by Glen Fryxell,
From Ingot to Target: A Cast Bullet Guide for Handgunners
While your there be sure to check out the other links to Cast Bullet Notes as well.