Will these fit my stock wheels, or do I need a special socket?

M12 x 1.5 is the standard metric thread for most modern vehicles. Your existing lug nut socket should fit these. If you're switching from a different thread pitch, measure your old nuts first.

Do I need to replace all four lug nuts at once?

Yes. Mix-and-match between aluminum and steel, or different shank styles, can cause uneven clamping load. Replace the full set to keep wheel pressure balanced.

How tight should I torque these?

Refer to your vehicle's service manual for the correct torque spec — it varies by make and model. Over-torquing aluminum nuts can strip the threads; under-torquing creates safety risk. Use a calibrated torque wrench.