16 bytex
The size of an IPv4 address is 32 bits, or 4 bytes.
IPv4 is 32 bit. 4 octets of 8 bits each.
IPv6 will increase the address space to 128bits. This will allow for around 3.4x1038 unique addresses. That's a lot. More then we could likely use in the foreseeable future. Of course we said that about IPv4 as well.
In theory, no, not necessarily, since ARP is flexible enough to be used to discover or describe a connection between other kinds of addresses, which don’t have to be the same lengths as IPv4 and Ethernet addresses.
There is no standard size.
32, 64
There is no standard window size.
What is the standard size of a sofa?
There is no standard size of a factory.
What is the standard-size large envelope?
The maximum permissible size for an IPv4 packet is 65,535 bytes, which includes both the header and the data payload. Since the maximum size of the header is 60 bytes, this allows for a maximum data payload of 65,475 bytes. However, in practical use, the Maximum Transmission Unit (MTU) often limits the size of packets on networks, typically to 1,500 bytes for Ethernet.
Modern computers usually have a word size of 16, 32, or 64 bits.