ill put my 2¢ in. it is a good idea to check the bio media once in a while* if you have a very heavy load and little room for the bio it can depending on how its set up get clogged but is uncommon to say the least. i just shake the bio media around to get any loose debris off an put it back.
i havent ever cleaned any of my impellers ever unless there was sand or something that was blocked and if that ever happends i just remove it get the obstruction out an replace it back and have had zero issues from that.
i also dont ever use prime on a wc only time i use that is for recharging my purigen. i fill my tanks up with the hose so there is a temp difference which isnt an issue unless you shock the system by filling to fast with super cold water, i just basicly mimic a rain storm an slightly bring down the temp, thankfully i have good tap water an can keep crs and other types directly in it.
best thing i can tell anyone is learn how it works and then why it works that way, after that you have the info to make a much better decision for your tank.