Planning my lens kit

[Fast Glass]

which has quite an aperture disadvantage; even if I compensate for the sensor sizes, it's still about a stop slower.

Just in case you didn't know, you lose 1 1/3rd stops of DOF with 1.6 crop camerasand 1.6 times worth of light and noise. Or about 1 1/3rd stops of light, if sensor technology is the same. In your case it's not, the 5D II has better per pixel image quality. So the differance is a little bigger than that.

(b) "exchanging" the 70-200 f/4 IS for a 70-200 f/2.8 II IS,

I'd go with this one, a 70-200mm f/2.8 II at 135mm has the same DOF and noise as you had on your Rebel.

Further, the 50 f/1.8 isn't bad on the 5D2

Yes, it isn't bad at all. I't'sa very good lens,the only thing really bad about it is the build quality, it's AF isprone to break the or the physical lens.

(after getting the 85 I rarely used it on the 500D)

But I thought you said you used that focal length and was bumed out that you don't have it anymore? Mabye not as much as your 50mm? If thats the case I will proceed with my assumtion.

If I get the 35L, rather than the 50L,

Yes, I'd get the 35mm f/1.4 L. You already have a not too bad 50mm prime and would be better served having a wider focal length range especially that your like 35mm anyway.

I'd have a very fast 35 and a quite fast 50, so I could exchange the 24-70 for a 24-105 IS because I'd use the primes for all non-staged non-flashed indoor shots which were a main reason to choose the f/2.8 zoom over the f/4,

Keep your 24-70mm, sometimes a zoom is madatory and having f/2.8 is a huge help. Plus it's quite a bit sharper at the 24-30mmend, and more similar inthe rest ofthe rangebut still sharper.

How is the f/1.4 or f/1.2 manageable in practice for non-staged shots, given that focus-and-recompose is impossible at those apertures,

That's not true, it is possible. Sometimes if you are not parallel, very closeto a smaller subject or changing the focus point drasticallyit will move your focus pointslightly, but most of the time it's possible.

That's quite some possibilities, even without touching the 100 macro, which I could get for photo-hiking where there's always something interesting that's too small for the 24-70's MM of 0.29,

I have a Minolta 100mm f/4 macro and that a great focal length for macro, but you could put extention tubes and get macro magnifications. Butother lenses are not optimised for very close workingdistancesso there is a reason toget a dedicatedmacro lens.Get 3rd party extention tubes, they are a lot cheaper andkenko air is no better than Canon air.[] I have Vivitar ex tubes and Minolta ex tubes and both work fine.

or the 17-40 which I might consider next summer if the 24 suddenly feels not wide enough for landscapes and similar.

I'd wait, learn your gear first. You might figure out you want a 600mm f/4 IS II Lin the mean time.[:P] Seriously, that's what happened to me. I was into the stuff you are in and latteron (about 2 years) I got into bird photography and it's been my main form of photography every since. Get what you want now but don't plan out to far becuase things can change in a hurry.


Chears,


John.