so what you are both saying is that the accidental written before the trill sign is definately referring to the upper auxillary of the trill (the E-natural in beat 3) and not to the first note of the trill (the D-natural).
Yes, the accidental on the trill sign is definitely referring to the upper auxillary note. (The D is already natural because of beat 6).
that is now the interpretation that i see (especially since we have a definate useage of the third note in measure 11). now, in my henle version - measure 11 starts with the upper note (auxillary) of the trill because of the previous note being the same F. why do i not like this? i just like to hear the F again. is this ok? so it would be F and then FGFGFGFGFEbGF (you see how it comes out perfectly even). please say yes. but, it's ok if you disagree.
I see 2 problems with starting the trill on the F: 1) Like you said, it is preceded by the F, and 2) The trill should start on the upper note.
Remember that it's a trill, not written out notes to be played exactly the same duration and an exact amount of notes (as I interpret the trill in this context). When you see a trill above a quarter note in boroque music, it means that the trill should have at minimum 4 smaller-duration notes, and resting on the principle note. You can trill with MORE notes than that, but that amount is required. Even more so in Beethoven's music, for this trill there is a minimum amount of ornamental notes required, but it is ok to add more notes, as long as the rhythm of the main beats is not altered. So if you end up with an uneven amount of 16th notes for this trill, add one. Richter actually plays a lot more notes here, making it sound as if he's playing 32nd notes for the trill -- and there is a bit of breathing room in the trill... it starts out slower, gets faster, then comes back to 16th notes for the last 3 notes in the measure. He also begins the trill with the appogiatura ON beat 7.
Wilhelm Kempff actually plays yet another lower appogiatura on this measure, keeping it consistant with the other instances of the trill.