There are fail-safes for the electric seats. For example, if they think something is 'in the way' of them moving they will move in 'inch-only' mode, same as with the auto-up drivers window (where installed/activated).
The sunroof does indeed have a manual turning (by way of an allen key in a slot somewhere near the switches I believe). There is no manual adjustment for the seats if they should fail.
As Phil says, electrics are as reliable as most other makes. Good maintenance and regular cleaning (to stop dirt/debris blocking motor runs and gearing) will all help to prolong the life of your car and it's gizmos
