For what it's worth this is my personal design, water comes in in the middle, falls over a baffle onto the filter sock, from there it goes under another baffle into the skimmer section , from the skimmer it goes over into the refugium, and back into the return section.
Most new skimmers have a drain plug located at the bottom of the collection cup, if not, its fairly easy to install one if your comfortable with diy projects. You can even install it with a barbed fitting to attach tubing to empty out in a separate container to make removal/cleaning easier and placed anywhere below the collection cup. Possibilities are numerous
Rock and macro is a great idea for your fuge, if your adding an algae scrubber as well there are two main things to consider, one- algae scrubbers work well but it will remove nutrients that your macro would use, not a big deal unless you want macro for feeding fish etc and scrubbers do require more maintenance then just pulling a chuck out of Chaeto when it's overgrown. Two-growing micro algae may also spread it around in small quantities throughout your system, I've thrown away lots of macro due to hair algae growing on it :/ try keeping it simple at first, see how your system responds to your fuge and consider if your design maintenance requirements are doable for your schedule. Good luck
