I use lee molds and what works for me is to smoke the molds each time with a candle and then I tap the molds with a stick to get all the projectiles to drop out.
I use an electric hot plate to pre-heat my mold. I do all my casting in my back driveway outside as weather permits - usually in the fall and early spring.
I never cast when it's raining or even when it's very humid. Even high humidity can cause steam voids to form in your castings.
I usually do a few hours of casting at once and make large batches that I then use throughout the year.
As a rule - I do not eat or drink whilst casting. I don't do anything with lead or casting in my kitchen. I've had my lead levels tested twice over the years and no issue was indicated either time.
I pre-process my scrap lead into ingots using an old metal pot either on a hot plate or on hot coals in a fire pit. I flux the scrap lead, remove any brass or steel or bullet jacket scrap and pour that into small ingots using a small muffin tin - perfect size to go into my lee smelter later. Also easier to transport as needed in my garage.
I use whatever lead scrap I come across. Fishing net weights, wheel weights, fired bullets, roofing lead, plumbers lead, stained glass lead. The only thing I avoid is battery lead as the battery acid can damage all sorts of things and I don't have a safe means to dispose of battery acid.