Typically, front wheel bearing/hubs and rear wheel bearings will need to be replaced around 100,000 miles. Ditto for front and rear struts. A squeak sound, when you turn, can be from the worn bearing on the top of the strut. If the boots on the half-axles are in good shape, and you're not hearing a clicking sound when you back up in small circles, they are likely okay. Ford half-axles are well made and very tough. Go with Timken wheel bearings, when you replace these components. There are a lot of inferior bearings on the market these days. Timken is usually the OEM for Ford.
Here's how to replace rear wheel bearings, which are easy to do:
https://www.askmehelpdesk.com/cars-t...ml#post1653648
Even though the instructions are for a Ford Taurus, the basic procedure is the same for your Focus. This might save you a little money. If the bearings are bad, you will likely see pronounced bluing around the hub--caused by intense heat.