Mainly in the afternoon, probably the early stages will be set around 11am I'm guessing. All except stage 1 are run twice, so you see the entire field through, then a break then they'll come past again. Then after the stage is re-opened you follow the officails out.
There are some freebies etc. Sometimes sponsors offer incentives to officials.

Nothing special needed, just a car that you don't mind driving on a gravel rally stage, food and drink for the afternoon and maybe a camera and Aerogard.