Doing a Service..... Some Qs

Going to do the oil and other filters on the CLK tomorrow.
I have
Oil & filter
Air filter
Cabin filter.

Now the questions.
Where is the cabin filter located?
When i reset the computer service interval, do i need to tell it what oil I've put in -I've seen something about that somewhere but can't find it. And how do i do it?

Thanks
Jim