+1 Aftermarket sway bars and endlinks make a huge improvement.
+1 Definitely get an alignment if you lower the car.
Lowering springs and aftermarket struts are a great way to go.
In response to the tire question, please allow me to direct you here:
Wheel / Tire FAQ
To answer your tire question, we need a little more information. What size wheels are you planning to mount them on? A 225 wide tire is just about the upper limit for a 17x7.0 wheel. A more suitable wheel for that size tire would be a 17x7.5 or 17x8.0 inch wide wheel. Whether or not they will work also depends on how much you are planning to lower your car.