I’m not sure I understand this. But there is a “Pay” button on the POS page. You’ll have to be more clear about this.
Probably discuss your ideas at New POS interface - Please contribute to the bounty :) [Now $1010!]
Isn’t this the “Sales invoice submitted sucessfully” message you want to remove?
You’ll most likely have to specify the areas which you think don’t work well currently and need improvement.