Well if you have aftermarket struts and or springs I don't think it matters when you take it in. As for the squealing it's probably just a belt that isn't on tight. It could be worse, but I'd check the belt first.
With the car running turn on the AC and watch it for a minute (not too long though). And see if it trips on and off, and when it makes the noise. Then spray a little belt dressing (just a little) on the belt.. if It's a very frequent noise you can just use water and listen. If the noise goes away for a while it's the belt thats causing the problems.
Edit: actually, maybe it will make noise if you turn it on and off a couple times.