@praveennoc,
1- The priority goes to the configured priority, if not which means that both switches will have the same default priority which is 100, so the priority goes to the higher IP address, so the multilayer switch that will have a higher IP address will be elected automatically as Active.
2- Preempt, first it's not enabled by default, and it means that if the Active router goes down, so the standby will go up, but what about if the Active come back to life again? if the preempt is enabled, so the Active that was down, once it will be up back it will take the control! if not, it will wait as a standby till the Active (that's standby in origin) to die that it will take its place!
3- FHRP, is very important lesson specially for the CCNP SW exam, usually a sim question is comming regarding HSRP, so give it some care!
Please, don't hesitate to ask if you have any inquiry, I will be so happy to support!
Also, please don't forget to RATE all helpful responses and MARK solutions!
Bst Rgds,
Andrew Khalil