Quote: "When they say that business establishments cannot use the free version, does that mean I can't sell games made with the free version?
"
No, but in the agreement you should also see something which is along the lines of "You can not use this prodcut for commercial use". That line means you cant sell what you make with it. Sorry.
Quote: "It was mentioned that DBPro Free 'is for single home users only', so if I uninstall DBPro 30 day trial from my initial PC, will I be able to install DBPro Free on my more powerful PC?"
you should be fine, what that line means is that DBPro free can not be used in any sort of company developing games and apps ect.