also heard from another reloader that if you let the last casting cool in the mold, it'll extend the mold life. I've been doing it for years now and mine work fine.
That's a holdover from using iron moulds- leaving the cavities full for storage ensures that the cavities are free and selaed from moisture. With Lee moulds (aluminum), it doesn't do much, but it can't hurt.
Wheel weights make for good cheap lead to cast- its soft enough for roundballs,or can be quenched in water to harden them fairly hard. For bullets with sharp narrow driving bands, add some lead/tin solder to the melt- I usually add about 18" of 50/50 solder wireper 10lbs of melted wheel weights. Tin helps with filling out moulds by slowing the lead from crystallizing.
A good cheap setup for starting would be a $8 hotplate from walmart and a small iron pot- I use such a set up for processing wheelweights into clean alloy, and a lee pro pot IV ($50)for casting. I use the propot because it had a bottom pour spout, but if you usea ladle such as Lyman ladle, you can use a hotplate/pot for casting.
A lyman cast bullet handbook is a really good investment before you start.
A very good website to visit- I spend countless hours there reading and learning is
http://castboolits.gunloads.com/Some of the people there are true experts.