FIM 2010 across multiple servers for HA

Experts,
For a very HA of FIM 2010 R2 following option is considered. Ideas is to have separate partition for administrative tasks and general users.

Admin partition:-
FIM Service and FIM Portal for admin partition
server1 & server2 (NLB name say FIM_SERVICE_ADMIN)
Server3 & server4 (NLB name say FIM_Portal_ADMIN)

User partition:-
FIM Service and FIM Portal for users
Server5 & Server6 (NLB name say FIM_SERVICE_Users)
Server7 & Server8 (NLB name say FIM_Portal_Users)

I am confused on how to go for installation.

1. What about the service account for FIM Service. Do I need to create two service account for FM Service. Using one account while installing FIM Service admin partition and using other service account while installing the FIM Service user partition? Is it possible?

2. What about share point foundation? Do I need to create two default website, one for admin partition and one for user partition? and again two service account for sharepoint application pool?
3. How SPN setting will go on?

Many more :(

Kindly guide me please.

Thanks,
Mann