Does anyone know whether the above changes are the same as the 5-minute failover interval that is discussed at below links? Just wondering if there are additional improvements that can still be made.
They're not the same. The keepalive changes only modify how long it takes before a dead connection is discovered.
You can find the failover interval value in the code section after the "Only switch pools if the failback pool has been" comment in cgminer.c.
It's 300 seconds by default, but I've lowered it to 60 seconds in my version.