No. Most eSIM profiles carry their network settings with them, and the operating system keeps its own database of settings as well, so the majority of installations come online without anyone opening that screen. Go near the APN only when data genuinely will not move, and only after you have checked profile selection, the roaming switch, and a restart.

No. The value belongs to the network a plan uses, not to the country. Two plans for the same destination can run on different networks and require different values, which is exactly why the answer has to come from the documentation for the plan you bought rather than from a general list someone compiled.

Not permanently. A wrong value stops data from flowing until you undo it, and undoing it means deleting the entry you created or restoring what was there. The real difficulty is not knowing what was there in the first place, which is why photographing the screen before you edit is worth the two seconds it takes.

Two possibilities. The first is that your plan may not permit tethering, a condition that varies by provider and by plan and has to be read from the plan's own details. The second is that some handsets use a separate settings entry for sharing. If the plan does allow it and the hotspot still fails, ask the provider before editing anything yourself.

You should not. Almost every value posted in a thread belongs to a different network or a different reseller, and entering one that does not match your plan usually turns a connection that was about to work into one that cannot — while adding a variable that makes the real cause harder to find. If your plan's documentation lists no value, ask the provider directly.

It is rarely the right move. Many QR codes install only once, so deleting a profile can leave you unable to reinstall it at all, and APN problems are solvable without deletion anyway. Contact the provider first, and delete only once you have confirmation that a replacement can be issued.