i have FD wheels on my protege, and the minimum spacer required is 3mm. and, thats just to bolt the wheel to the hub. because the bore shape is different on the wheels, you need the spacer to properly mount the wheel to the hub. the wheels will physically fit without spacers, but they wont mate correctly to the hub face without the spacer.
as for tire size, the narrowest tire i would consider is a 205. i run 215/45's and have no issue with clearance to the strut or fender. (i am lowered 1.5" front and rear too) i would suspect you could run a 225/45 without much difficulty, but that size doesnt have as many options.