It is not a problem to to change the oil yourself.
I watched the tech do it. And it is easy to do on the S65 V8.
If you are serious about servicing your car. I would pay $30 (in the US ) to have access to bmwtechinfo.com for a day. Leave your self lots of time-- the site is not particularly userfriendly.
There you can see pictures of the procedure and all the others that interest you. This is what I did. For the service manual they don't allow you to download any of it, so I can't attach a picture. However, you can print out the pages that interest you.
The M5 and M6 V10 have a dry sump. I have heard that, in order the change the oil according to the factory procedures you have to activate an electric pump throught the BMW Service Computer. This is unverifed info.
However, I know for sure that to change all of the oil in the M3 6 speed transmission, they activated the electric circulating pump (that goes to the transmission oil cooler) through the Service Computer. This was as described in the online service manual.
But nothing like that is required for the M3 engine oil.
On the M3, there are two wet sumps. You drain each with its own drain plugs --There are two drain plugs. You use a hex (allen head) socket. The tightening torque is 25NM-18 ft/lbs. Get the oil filter and the two sealing rings are included, at least in the US. They should be replaced each time.
There are cutouts in the aluminum M3 specific strengthing plate for the two drain plugs.
You change the oil filter from the top like any other cartridge BMW.
Make sure you use the BMW specified oil. You can see the oil and amounts in my sticky memo at the beginning of this maintenance section.
Hope that helps,
Rob from San Diego.