If it is past the regulator, then it is regulated, low pressure. As is generally how they are installed. Be aware not all LP devices will work, especially if they come with their own regulator, even if you take out that regulator. Many different products, many different pressures. There are a whole line of grills/cookers/burners set up to work off the low side of an RV, and most already have the quick connect installed.
No,you do not want to hook up a LP tank to this,you would probably damage your regulator. You need to install an extend-a-stay kit.