1. I, also, had a bad experience with Sid's and won't go there again.
With your setup, I'd recommend -1.8 front, -1.5 rear. For a less tailhappy car, you could also do -1.8 front and rear, or -1.5 front and rear . Take your swaybar setup into consideration too. If you combine one of those three camber suggestions (or similar) with zero toe, all around, you won't see any uneven or increased tire wear, but will have a well balanced wagon. -1.5 in the rear should allow you to fit the tires without rubbing, especially if you have your fenders rolled. -1.8 might be necessary without a role.
Theoretically, I'm currently running about -1.5 in the rear, -1.8 in the front with no rubbing from my 245/40/17's on 17X8 +48 with rolled fenders (aside from a slight rub of the front fender liner at full lock). Before I rolled the fenders, I ran 225's. I didn't rub as long as I ran about -1.8 in the rear. I ran -2.2 in the front.
Disclaimer: Take these specs with a grain of salt since they were all on C&C's alignment rack, which may or may not be calibrated similarly to the alignment rack you end up on. Also, all WRX wagons are not created equally, though I'm not aware of any tire clearance/balance differences between our cars' MY.
2. Autozone has the correct spring compressor kit and you can borrow it for free. They also have the incorrect kit, so make sure you get the right one. The correct ones look like this:
Feel free to use an impact wrench/drill on them like in the pic, works great.
3. Cory.
If you do it yourself, an impact wrench would help a lot with R&R of the top strut bolt, but most strut manufactures tell you not to use one because you can damage the strut. I feel it's fine for removal and probably for reinstallation, if you're very careful not to exceed the proper torque specs. You can also do it with a breaker bar (borrow one from AutoZone if you don’t have one). But with a breaker bar, most of the time, you need to secure the strut shaft from spinning. Supposedly a strap wrench is the correct way to do this, but I’ve never been able to get one to grip. Instead, I use Vicegrips with an inner tube (from a bicycle) and a rag between the Vicegrips and the shaft. I also grip it as far up as I can, just in case the surface of the shaft is marred by the Vicegrips. This method has always worked well for me.
4. In the rear, you only need one set of camber bolts. I’ve always used Ingalls from Summit. They go in the top holes.
In the front, you’ll likely only be able to get about -1 degree of camber with the stock camber bolts. That may be fine for you since you don’t race and don’t want the car to tramline. If you want more, or will primarily be driving fast around corners (and don’t want uneven tire wear), you’ll want more (see part 1. of this post). You can do camber plates or go the more budget friendly way as I’ve done, and add aftermarket bolts (same type as you use in the rear) to the bottom holes in the front. Tell you alignment guy to max out the aftermarket camber bolts for negative camber (so they’re less likely to slip) and then use the OEM camber bolts in the top holes to adjust from there. The OEM bolts take something like 120 Lb/ft of torque but the thinner aftermarket bolts can only take about 80 Lb/ft so they’re more prone to slippage. That said, I’ve never had a problem and I’ve raced and daily driven my car with this setup for over half a decade. I do drive off road and hit potholes too.
Hope that helps.
Oh, and be very careful not to overtorque the 3 tophat nuts on each corner. The correct torque is like 12 Lb/Ft so use a tiny ratchet or a trustworthy torque wrench. Retorque all 4 nuts on each corner to spec after a week or so of driving after everything settles.