unless you know someone who works for mercedes/smart then there isnt much for technical guides, workshop maintenance available for the forfour other than what you can find here.
as for servicing, the service schedule is A (single spanner),B (double spanner),A,B
A is oil, oil filter and pollen filter
B is oil, oil filter, pollen filter, air filter, spark plugs*, fuel filter**
* only petrol engines
** only diesel engines
*NOTE* petrol engines DO NOT have a fuel filter
valve clearances on all petrols (excluding brabus) every 60,000 miles (96,000 km)
on a brabus the cam belt requires changing at 60,000 miles (96,000 km) or 6 years