Once you have a solid jig , your biggest problem is spreading the lead around by handling it. You'd be surprised how much just flakes off or rubs off on your hands. Look at your hands when you are done. You hands or gloves will be dirty. That's almost all just lead rubbing off.. Just handling the lead around the stove will leave residue behind. Actual particles and some lead and lead oxide from your hands getting all over the place. There would also be some vapor deposited but that would depend on how hot you got the lead and to some extend for how long. Actual droppings and touching would probably spread way more lead as long as you don't get it too hot. The real problems with fumes would be if you were melting. Very small differences in temps above the melting point cause the vapor pressure to go up dramatically. You could work with lead just above its melting point for a long time but if you go 300 degrees above its melting point (easy to do if you aren't careful) , you would get sick fast. I also never melt indoors.
I don't think I'd do lead jigs in my kitchen (unless I really needed some jigs fast!!
). If you've done it , I wouldn't lose sleep over it either. Its just not a good idea.