1. I would stick to tin - the first person to start drooling otherwise would be you, from the vapors caused by melting masses of lead.
2. You are more likely to get anxious scrutiny from your tax advisor or insurance underwriter, especially if you're setting up the casting as a separate business entity.
3. Check your local ordnances to see what they have to say about running a business on your home premises. Depending on your local government, they may take 2 attitudes: the proscriptive and the descriptive. Proscriptive says "primary residences can't be used for a business purpose" or words to that effect. Descriptive details the conditions they want to avoid when they say that: "You may not operate any activity that causes noise, fumes, traffic problems, etc, etc". It's far easier to satisfy a descriptive ordnance in most cases.
Practically, your supplies will be delivered by FedEx or the equivalent. You ship by the same method. A well-run casting operation of "hobby scale" is probably far less disruptive than a neighbor who fixes cars in the driveway, or owns a large moody dog, or has a woodworking shop with power tools in his shed. Just keep the blood-curdling screams and maniacal laughter (as you plot world domination) to a minimum, I think.