If the channel is busy, the station waits a random amount of time before sensing the channel again. Of course few hosts, or hosts that use the channel infrequently will do well with 1-persist. If a slot is idle, the station transmits with probability p . If collision occurs, transmission is still going. Therefore it needs error control.
Nodes abort their transmission as soon as they detect a collision.
Not immediately since there will be another collision. Wait for some random interval before retransmitting. Ethernet evolved in Xerox. IEEE 802.4 defines the token bus standard. IEEE 802.5 defines the token ring standard.