Haha this is pretty funny!

Can you restore it back to factory default: Not by formatting the wii, as even then softmods dont go but if you have bootmii installed as boot2 and do a backup before installing any softmods, then i guess you could restore it back to default.(With the exception of having bootmii)

What is bricked: When you brick your wii, it is very bad thing. It can be caused by accident by removing the system menu's ios or on purpose by updates implied by nintendo. Generally installing dodgy things after softmodding can cause it. But if you stick to reliable tutorials then you should be ok. Also if you have a console which was built after late 2006 and before late 2007 then you will be able to install bootmii as boot2. This will basically make your wii brick proof as it boots up before the nand(system menu) so if you did brick it you could restore your wii using bootmii(Only if you madea backup earlier on and kept it somewhere safe)

Can you fix it if gets bricked: Bootmii boot2, look at the answer above.

Disc updates: If your going to use usb loaders or backup launchers these skip updates. But if you want to use the proper channel with a game that requires an update it is a little risky. Sometimes games need to update there ios to a newer version as it adds new features.
75% of the time it is ok to update as it is updating an ios that is not part of the softmod. But the other 25% of the time it does updates an ios which is part of your softmod. If it does update it then you will lose your softmods and could end up with a semi brick. An easier way round this is to find out the games ios off the internet, then find out if it is part of the softmods you have installed, then if its not then just update it through the channel.

The best website for wii modding and which helped me years ago is:
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There are great tuts there and lots of information.