Please add documentation about how "Disabled" host works. Currently it is very limited to "Disabled" - not monitored.

Something like this should suffice:
"Disabled" state means that indeed host is no longer monitored. For passive checks ( Zabbix agent, ICMP, SNMP, etc. - all checks going from server to the target device ) that means server/proxy will not do those checks at all. Monitoring stops as soon as you disable the host.

For active checks - Zabbix agent receives configuration every two minutes by default, that means as soon as new configuration is received with the host being disabled, agent stops monitoring active checks. In the time interval (<2 min) that happens before Zabbix agent understands that it no longer needs to monitor something, the server will just reject the incoming data.