I just did my 1st oil change and replaced 6 of the 12 spark plugs with NGK platinum tipped (apparently guaranteed for 100,000km)
I think that you are referring to the MAF. It is not normal to run with it disconnected.
1.Is there anything one can do to improve the idling problem?
Air filters OK?
2.Do all 12 spark plugs work all the time? (maybe a dumb question but I never was aware it had double spark plugs, the ones we removed were bosch and still looked fine.)
Well, they work in sequenced pairs, of course. Dual spark plug pairs fire together during the lower & partial load range. At medium & higher load ranges, the dual spark plug timing is staggered by 10 deg.
3.The ATF dip stick needs a special tool to remove, is there a trick or a tool one can acquire? Pretty stupid IMO that one cannot check this ATF level. Or is there a valid reason for this?
ATF is not 'burned' as is engine oil, so apart from a leak, there is no reason for any consumption. A dipstick would help though, to keep an eye on it's appearance/smell.
4.Lastly, the C280 has the adjustment on the headlights that allows you to remotely adjust the beam like when you have a trailer, this just stopped working recently, any tips would be appreciated. I assume this works with the vacuum system as this only works when the car is idling or traveling w/o being in acceleration mode.
A page from the WIS that describes the operation is below. Could be a vacuum line fault.
I am pretty technical savvy having serviced cars, done engine overhauls in the distant past (getting old)
Me too! You have the first of the wonderful M112 V6 engines. I have one of the last in my 2004 CLK.