How do you know if you have bad CV joints

I have 98 Galant. 120,000 miles on it. I keep up with perventive maintance. I just had a squeaky noise when I turn left only. The slightest movement of my steering wheel to the left I hear the noise. I have had my tires checked and balanced, checked power steering fluid and had brakes checked.

Would bad cv joints cause the noise?

Also if I go beyond 50 mph I have serious vibration in my steering wheel. What might cause this? Had engine mounts checked they are ok