>>106906949
You forgot DHCP. SLAAC is much better and does not need a centralised server.

>>106907015
>if it was just IPv4 but with 128-bit addresses.
It is. It's 4 times the size.
The way it works is actually way more simpler because the larger address size solves a lot problems on its own.
It's written in hex because otherwise it would be too long to write.
If you want you can write an IPv4 using IPv6 notation:
192.168.1.1 would be ::c0a8:101.
192 is c0
168 is a8
1 is 1
01 is 1
You can also do the reverse and use IPv4 notation on a IPv6.
One of 4chan's IPv6 is 2606:4700::6813:ea20 which would be 38.6.71.0.0.0.0.0.0.0.0.0.104.19.234.32 using IPv4 notation.
As you can see, hexadecimal is much more compact.
IPv4 notation on an IPv6 address is not officially supported so it is not being used anywhere.

>>106907782
>>106907805
IPv6 addresses are ephemeral by default. A device can have multiple addresses, an IPv6 usually lasts 1 to 5 hours if not statically assigned.
If an ISP is not retarded it will give you at least a /64 subnet, which means the first half will be decided by your ISP and the second half is decided by you, your router or your devices, according to your configuration.
I have a /56 which means my ISP controls the first 56 bits of the address and I control the remaining 72 bits.