AP upgrade, what needs to be replaced?

I have a 2001 Simrad system on my 42' sailboat. The control unit had a crack and got saturated and it fried. Replacement parts impossible to find and about $1K if you do. So, thinking to upgrade the whole thing with RayMarine as we upgraded everything else over the lat two years (sailing instruments, eS7, radar, VHF, ect.).

My question is; what do I have to replace?

1. Compass - yes
2. Control Head - yes
3. Pump - I don't know
4. Ram - I don't know
5. Rudder position indicator - I assume so
6. Resvervoir - I don't know

Can you please help with #s 3, 4, 5 & 6?

Thanks,

Barry