Squat - you are correct - don't lift the chest on the way up keep driving with the hips. Shove your knees out harder.
Press - I would walk it out the other way, so you face the wall. You don't want to be stepping backwards without having a view of where the bar needs to be placed after the set. They look solid but I would focus a little more on squeezing the armpits tight
DL - Yes stand taller at the top and lock out better. Do you have more mats? You may be getting into block pull territory with the elevation