Hammer and chisel work best for me. Dull chisel splits better than a sharp chisel. I would probably take off a few fingers with a hatchet. Some of the chunks from smokinlicious are just a touch too big to fit in the smoke box to get the lid down all the way. So I'm often splitting them into a variety of sizes. The size of the chunks depends on what I'm smoking. If it's a long smoke like brisket or butt, I try to keep the chunks larger. If it's a shorter smoke like chicken, I'll split the chunks so they are around 1-2 ounces. For ribs, maybe about 2 ounces or so per chunk. For fish or something where you might consider chips, I will split thin shards (rather than using those dry ole chips you can buy). I often like to use a combination of larger and smaller chunks in a single smoke. So, I just choose a combination of chunk sizes, measured by total weight, that is appropriate for what I'm smoking. I might split a few chunks down, then pick and choose and put the unused splits back in the box for later use.
The total amount of wood is personal taste. I like things on the smoky side. So 6-7 ounces for butt or brisket, 5-6 ounces for ribs, 3-4 ounces for chicken. Those are good for me. They might be on the high side for some. It also depends on the species of wood. Hickory and mesquite will be stronger, maple, pecan and fruit woods will be milder. You might find you want to start with a little less, then add more wood as you see fit. The smoking guide in the first post of the link below has pretty good recommendations for where to start.
http://smokinitforums.com/index.php?topic=2151.0