When my upper ball joint went bad I replaced upper and lower on both sides.I also upgraded to greaseable joints. My theory was I'm already dirty and if one went bad the others can't be too far behind. You will need a ball joint press to r&r the lower joints. Most auto part stores rent them. The upper are just new control arms, super easy to replace.
Roll a floor jack under the lower control arm and jack until the tire is a few inches off the ground, now the lower ball joint is holding the spindle up. Insert long pry bar under tire and use it to lift the wheel tire spindle and you are looking for excessive play in that lower ball joint.
Alternatively, you can lay under the front with a jack under the LCA and place a finger against the spindle at the lower ball joint so you can feel if any movement as you or an assistant slowly jacks the LCA to transfer load on lower ball joint.
Like Dano said you are already dirty may as well do them all. I just did the uppers, lowers and inner and outer tie rod ends. like Dano said the uppers are super easy the lowers a bit of a pain but with a ball joint press it makes it bearable. Up in the Great white north here in Canada you can rent a ball joint press with all the adaptors, they charge you for the cost of it and refund the cost when you return the kit. as far as if you are going to replace the tie rod ends i would recommend doing inner and outers. FYI dont bother with the inner tie rod boots if yours look okay, but the factory steel band that holds the boot to the steering rack can be held with a thinner tie wrap. When you screw the inner and outer together and screw it into the steering rack on each side, before you remove ballpark a measurment of the total length of the assembly on each side from where it screws into the steering rack. Whether or not you do tie rods or not, DO get an alignment.