for the deadlifts, whatever form you use, just keep four back straight
it's so f**king hard, but if not, you ll just f**k your back for a long time
it's obvious you ll have a lot stability if you do lifts without shoes
as you optimize the contact between the floor and your feet
someone told me lifting with regular shoes is like lifting while standing on a mattress
a lot of your strenght will be lost in the softness of the sole (specially at the heel section)
I use shoes with super thin soles and it works really well