The simplest way is to use a tank with a power filter, no substrate, and some PVC
for hiding spots and a heater. As far as cycling goes, just pull some media from the filter in your display tank or keep a sponge filter or foam block in your sump. When you need to QT your new guys, just drop the foam into the power filter. (If the new fish show signs of disease, do NOT put the foam or sponge back into your main tank or sump. Just throw it out.)
Keep new fish in quarantine for at least a week (longer is better). If they come down with something, you treat it in QT and don't make your established fish sick. You also don't have to worry about killing your inverts with meds. Also, catching a fish out of a display tank is often near impossible. The sponge / foam is to minimize cycle time on the QT by transferring some beneficial bacteria over.