You're correct. The driver can edit everything except line 3. This is outlined in the regs. Companies can edit the ELOGs as well. There are a few urban myths with ELOGs,
1) You automatically get CSA points if you violate a reg with an ELOG.
Not true. The ELOG is directly linked to the carrier, and no one else.
2) ELOGs will prevent HOS violations.
Not true. ELOGs will flag a violation making it easier for an LEO to spot, but they do nothing to stop them from happening besides warn the driver when he/she is close to running out of hours. If the driver keeps on going, the ELOG won't do anything. It won't shut off the truck, hit you on the head with a hammer, etc.