Work out first and last usable ip instantly with clear inputs, formula shown and shareable results.
Once the network address is known, the first assignable host is one above it and the last is one below the broadcast address. For a /31 and /32 there is no broadcast to skip, so the whole block is assignable. This is the range you hand to a DHCP scope or a static addressing sheet.
Usable range
first = network + 1; last = broadcast - 1 (for prefix <= 30)
Yes. The default gateway must be an assignable host address, and by convention it is the first or last usable address in the subnet.
A /32 has no host bits, so it describes exactly one interface — commonly a loopback or a host route — and there is no network or broadcast address to exclude.