You got a great deal on that machine. That is the largest machine Miele has ever made, even the new S8, with the same size bag and motor, is substantially smaller and probably weigh half as much. That machine retailed with SEB236 (Biggest Nozzle) For around 1200 dollars when it was new, so you definitely got a good deal on it. It takes the G/N Style dust bags, which are the largest they make. I think it's a rule to only use genuine bags and filters in a Miele. Using Envirocare or knock off bags, as good as they may be when compared to other OEM bags, just do not compare to the 9 layer AirClean bags that Miele makes. They have self-sealing collar, instead of the old style that sealed whenever you pulled them out, still causing a dirt poof. The genuine G/N bag package will include the pre-motor filter with it. The HEPA filter should probably be replaced as the last order of genuine filters that came in, that still were the Active HEPA, didn't have Miele written into the filter frame on them, and I don't think they've done that in quite sometime. The new HEPA Filters don't have the carbon in them, but they have increased the filtration area so they're going to 99.9% down to .01 micron, where the last one, was only down to .03 microns.
I'm a Miele dealer so if you need anything, just send me an email and I can get them sent out to you...or if you don't want to keep this, hit me up and I'll buy it from you.
Evan