Well Nick, since you opened that one up....!
Contracts always arrive weeks before the first day of preproduction, properly signed by the appropriate parties.
All items discussed at the interview/in the deal memo are correctly represented in the rider and/or LOA.
Reimbursement for cell phone costs, ground transportation and personal technology is automatically rider'ed in, and the employment packet contains proof of insurance for all personal technology used in support of the production (your laptop, your MS Office license, your cell phone, iPod, speakers, iPad, video camera...) as well as a kit fee.