you'll need to roll fenders. Those will clear wrx brakes just fine, however they will not clear brembos without a spacer if you ever decide to upgrade.
what the **** do you want -4* camber for? That is completely unnecessary and unneeded.
If you are scared of modifying your fenders, you WILL have to stretch your tires. If you did some research, you'll see that it decreases overall grip and will aid the tires in breaking loose (due to a super stiff sidewall). Theres always the chance of popping a bead on a pothole as well. The point of stretching tires is to GO LOW, so if you are at stock height....I'd walk away from this.
It wont effect the suspension, but it will look immensely stupid unless you are on coilovers and LOW. There are a few examples of people buying aggressive fitments on stock suspension in the Members Car Gallery, and it looks retarded. Aggressive fitments on subarus covers alot of points in order for to get the look you want. Camber (not -4*, but you will need to run 2*+ depending..), ride height (LOW), willingness to modify fenders (roll, pull, etc), and a proper suspension set-up that can handle all of that.
This isn't a super friendly fitment if you don't understand all the characteristics that go into this type of set-up.