1). Will the changes made on Master( during the time back in INOPERABLE state) be auto copied to Backup ? or some manual command needs to be run?
Vikas : Yes, nothing extra needed to sync the config.
2). What's the track IP option used for? do i need to track any IP?
Vikas: Track-ip is another mechanism to initiate failover if it fails. Device pings/probes a configured IP and if fails then failover is initiated.
https://kb.juniper.net/InfoCenter/index?page=content&id=KB11357&actp=METADATA
https://www.juniper.net/documentation/software/screenos/screenos6.3.0/630_ce_HA.pdf
3). What is the function of rto-mirror? what info it gives us ?
Vikas: https://kb.juniper.net/InfoCenter/index?page=content&id=KB7039&act=login
4). I have another interface which i want to track/monitor, Do i need another VSD group?
Vikas : Not needed if you are not using any other vsd except default vsd 0 .
Thanks,
Vikas