If one strut is worn the other isn't far behind so yes replace both of them. Then you need to determine if any other part of the front end is worn like the ball joints, control arm bushings, tie rod ends and wheel bearings. All those have to be in good shape for a proper wheel alignment.
There's different strokes for different folks. Some replace things as they break while others do preventive maintenance. I like to know my stuff is right and hopefully not break down on the road so I'm one that would replace everything. That logic applies to the suspension as they are all moving parts that work together. If you have a bad ball joint you can almost guarantee the other ball joints and tierods are close to worn out. Do you want to replace them one at a time or get it over with?
Advance, AutoZone and O'Reillys has a free tool loaner program with a deposit. There you can borrow a strut spring compressor. Don't confuse it with the coil spring compressor they have as they work the opposite. One clamps inside the spring while the other on the outer.
You'll also need the strut mounts which you see attached to the fender walls. The center nut on them holds the assembly together so don't remove that nut without compressing the spring or you could get hurt. If you never done it before you need to learn how first by the manual or a YouTube video.
Brands? Most here prefer the KYB struts. I bought the Monroes for mine because they were on sale. They have served me well.
Check out Rock Auto, Advance or Amazon for deals. TRT41 code gets you $40 off $100 at Advances website.
