oil/tranny fluid changes?
 

Hello all, I am VERY new here as this is only my second post...also I did a search first but found nothing for my question...?
I am a mechanical guy and want to change my oil and tranny fluid on my ML350 we just bought, and I have a couple of questions that the owners manual didn't cover.

First: is the oil filter in the front of the drivers side of the motor the ONLY filter to change?? I don't see one anywhere "UNDER" the the motor like I am used to on my other cars.also along with that the filter I am looking to buy comes with 3 o-rings... is the large one is to replace the one on the cap??? So what are the other 2 for? I have NOT drained the oil yet as I wanted to find out all I needed to know before I did that.

Second: The transmission...There isn't a dipstick?!?!?!? HUH, WHAT?? How do you check your fluid level?
When I go to change the fluid and filter I will replace the filter and the pan gasket, and "top off" the fluid level, but how do I know when I have topped off enough?
I called my MB dealership today (saturday), but ONLY salespeople there and no one had an answer for me.
Thanks in advance, Ken (a new and -so far- happy ML owner)