Hiya, mith! As you've seen, there are more different sets of advice than there are smokers. I'd say one safe rule of thumb would be to follow the shop owner's advice till you start to feel comfortable with a routine. A Czech tool is useful for a lot of things, but I wouldn't use it for reaming. That goes triple for a pocket knife. Best thing to use is always a reamer.
You can run a cleaner through it without taking the stem out, do it, otherwise wait till it's cool. I use at least one, sometimes two bristle cleaners after every smoke, & leave the second one in till I'm ready to smoke it again. (The bristles help clean out any loose bits of tobacco & tars.) When the cleaner comes out mostly dry & clean, you're good.
A stem should be ok in a pouch/sleeve/pipe-sock/etc., but if it makes you edgy, take it apart. (If you start buying estate pipes or new ones online, a good seller will wrap the pieces separately in bubble wrap or paper to protect in shipping. Most times if you're carrying your own with you, you should be ok leaving it assembled. There's more, but you've probably read enough for right now.
You can run a cleaner through it without taking the stem out, do it, otherwise wait till it's cool. I use at least one, sometimes two bristle cleaners after every smoke, & leave the second one in till I'm ready to smoke it again. (The bristles help clean out any loose bits of tobacco & tars.) When the cleaner comes out mostly dry & clean, you're good.
A stem should be ok in a pouch/sleeve/pipe-sock/etc., but if it makes you edgy, take it apart. (If you start buying estate pipes or new ones online, a good seller will wrap the pieces separately in bubble wrap or paper to protect in shipping. Most times if you're carrying your own with you, you should be ok leaving it assembled. There's more, but you've probably read enough for right now.