i am by no means an expert, but i would guess you could just put them in the pot and melt them. It would prob be nice if you could figure out what the chalky stuff was though. Perhaps there's a way to clean them before putting them into the pot. just make sure they are DRY if you do wash them off.

You could do practice pours if you wanted. I will make several practice pours before I start putting the hooks into the molds just to make sure the molds are heated up. The smaller jigs are a little trickier to pour because of how little space there is in the cavity. From what I've learned, you have to pay more attention to make sure the lead pours directly into the hole and doesn't break stream or the jig will not come out perfectly.