Can someone help me with their thoughts on shed electrics.

I want to run electric to my shed, and am planning to use 2.5mm SWA
cable so its protected. How deep should I bury it - I can do this
under a hedge so should avoid random spade attack etc.

I want to run 1 internal double socket, I IP55 external socket, 1
internal strip light and an external PIR light.

Real questions a-

1) What should the MCB rating be at the house consumer unit and should
it be RCD protected?

2) Do I need to add another consumer unit in the shed? If so what
should the maximum RCD rating be on this?

3) Should I add a local earth rod? If so what guage of earth wire
should I use to connect to it?

4) Is there an electrical book that I can read, that can help me with
this kind of question in the future?

Thanks

Quigs