brake linings should be checked at 15,000 and 25,000 miles and then every 5,000 miles after that.
With each brake job.
every 7500 miles or 12 months
that depends on how often you drive. best way to determine if brakes need changing, is to look at brake fluid resevoir. if level is low, your linings are worn and either need replacing or renewing
The brake system along with a complete safety inspection of the vehicle should be done at each oil change (aprox every 5K or once a year).
DailyDaily
monthly
Commercially speaking, in the UK they have to be checked annually, and signed.
Remove the brake rotor and have it checked at a reputable auto parts retailer. Rotors often warp with age, especially if they have been overheated.
Every time it is worn!
every 4 weeks in the community
Every time it is worn.
Every time the PFD is worn