Would bad front struts cause my vehicle to shake while driving 55+?

Tire balance

Seems like you may have multiple issues. If vehicle bottoms out when you hit dips could be the front struts. Also if the struts are that bad, it can cause tires to bounce like a basket ball being dribbled which can feel like a vibration. As far as the grinding sound, you will nee to take it in for a visual inspection.