For your engine oil; I'm using 5w40 syn. I got a Mahle filter from my local euro garage. I believe that it's 4.5 l to fill; but not 100% sure on that one. That's what I put in mine the last time to bring the level up to full.
Don't know about the tranny fluid cause the garage did a change for me when they did my clutch last year.
Hope that helps!
'95 325is - //M Body - Shark Injected - Sport Pkg - Depo's with HID's