Which fixtures connect
Generally, fixtures that can discharge grease: pot and prep sinks, floor drains in cooking areas, mop sinks, and often dishwashers (depending on local rules). Restrooms and most hand sinks do not.
How sizing works
Sizing methods vary by jurisdiction. Common approaches use fixture flow rates and drainage time, or meal counts and operating hours. Your utility's pretreatment program decides which method applies.
Reusing an existing interceptor
Second-generation spaces often come with an interceptor. Verify size, condition, connections and pumping access before you sign the lease, because a replacement in a finished parking lot is expensive.
Backflow too
Beverage, ice, irrigation and fire lines may each need backflow assemblies.
Get a grease and backflow review before permit.