Firstly, you should never post your full serial online or anywhere else. It is not necessary and you risk leaking your console's private information to other people.
Secondly, if your console is unpatched, then your firmware is irrelevant as the exploit used is based on the hardware of the console. This exploit requires you to insert a piece of metal or something conductive into your right Joy-Con rail to put the console into RCM in order to hack it. On eBay, jigs can be found if you do not have anything conductive at home.
Thirdly, emuMMC is running a copy of your console from an SD card. This can be used to help stave off bans as emuMMC acts like a second console without actually owning one. It does not matter if you use CFW on sysMMC or emuMMC as long as the one where you use CFW does not go online.
Depends. Sometimes the games will still work without the updates, other times the games will ask for updates but still allow you to play them, and there are times where they will not launch without an update.