For Italian sausage I wouldn't emulsify the meat block before stuffing. You want a nice grind, typically we do 4mm for final grind size. I'd also add red papper flakes to your seasoning.
For your casings, rinse them good, then soak them in 100 degree F water for at least 1 hour minimum. Change the water every 30 min or so. In a sausage production setting, typically there is 100 degree water running constantly through the holding tub. You want the casing to be well hydrated and the warmth makes them less likely to break and be brittle.
For cooking them, no, do not puncture the casing. If you need to puncture the casing to keep them from bursting you are either stuffing them too tight or cooking them at too high of heat, or both. For italian sausage I take a pan or skillet, and place the sausages in the pan. Pour sprite or 7 up in the pan so that the sausages have liquid about half way up them. Simmer the sausages covered over medium - medium low heat turning every 5 min or so. after 10-15 min, the sprite should be pretty well reduced down to nothing, then you will get a nice browning on the sausages. Once one side is browned, flip it and let the other side brown for a couple minutes and you will be all set.