SQ: Your elbows are jacked up pretty high. Have you tried thumb on top of the bar with a slightly wider grip? Also, try and take a breath that bears down on your abs so your back is flat. Lean over more at the start and keep your back in that flat position - don't pull up with your chest on the way up - use your hips. I would dial this all in first before trying to assess the R/L weight shifting.
DL: Get your setup consistency with every rep (knees flush with front of arms) and LOCK that setup into place before you squeeze your back. Nothing else should move when you flatten your back. If your grip is going you can switch to hook, but it will likely have to be trained with lighter weights for a while first (it is painful). Most people will switch to a mixed grip. I would put off using straps for the time being. You should be able to get to much higher weight before needing those.