Firstly, normally nodes base their automatic IPv6 address on their MAC address, so there will be no conflict between these, since MAC addresses are supposed to be unique to the hardware. Otherwise, it’s a random 64-bit number (actually a few less bits, but not many). It’s very unlikely a collision will happen. And even if it does, there is a protocol (Duplicate Address Detection) to detect it, and avoid it.

Unlike in IPv4, in IPv6 there is a lower risk of nodes assigning the same IPv6 address if there's no central DHCP. This is because IPv6 uses a unique interface identifier (IID) that is automatically generated by the node based on its MAC address and a random value. This makes it highly unlikely that two nodes on the same network would generate the same IID and therefore, the same IPv6 address.

Don't worry coz DAD (Duplicate Address Detection) will come to your rescue :p

Not if you don't have same MAC in the network .

SLAAC reserves bottom 64 bits for autoconfiguration, and while incredibly wasteful it does ensure every MAC can have its own IP address

You can generate sqrt(2^64) random suffixes before the probability of collision becomes significant. That number is in the billions for a single /64 network.

In other words, no.