Hi,
To access the oil filter housing you will have to move the coolant reservoir
out of the way, it is simply held on with the visible 8mm screw. Once the 8mm screw is removed simply lift the coolant bottle and tilt itaway at about 45 degrees.
Sometimes there is a small plastic ring around the filter housing nut, which for some reason isn't on all of them, just remove it. If I remember rightly you'll need a 27mm socket to undo the housing, a decent length extention is also handy. You are right about the oil leaking out so be careful only to wind the housing out far enough to break the seal allowing the oil inside to drain don to the sump, otherwise you'll just end up with a mess all down the side of your gearbox. Best to drain the oil from the sump before completely removing it.
The sump drain bung is either an 8 or 10mm allen key. Oil will begin to come out the second you crack it off so be careful if it's hot and have something underneath to catch it. Make sure you replace the sump plug washer.
Be sure to always replace the seal on the filter housing as these are notorious for leaking!
Here's a link with some nice pictures to help you out.....
LINK
If you eed anymore help please ask.
Rich.
BMW Technician
5 years main dealer experience.