Re: Body position for receiving
Speaking about ukemi.... nice pretty breakfalls are over-rated, over emphasized and over the top unrealistic except to show ones' aerial acrobat abilities.
When I was in a aikikai dojo once upon a time, I and many of my sempai(s) love doing pretty breakfalls. We would throw uke in a projecting manner and the uke would execute a pretty aerial acrobatic breakfall. Impress the ladies, you know.
Fast forward to my current dojo... sensei's technique just doesn't allow us to do pretty breakfalls. He keeps it tight and close and there is a feeling that there is just not space to flip over. Hence we just fall, like a sack of potatoes... with a dull thud! Not impressive, not pretty but still able to get up to continue our attack.
When dealing with uke who doesn't want to over commit their attack, some of the methods include
1) atemi to create an opening.
2) Entering deep (deep irimi) to upset uke's tempo and balance (kuzushi)
3) Use deception, for example pretending to attack his upper body, but in actuality, going for a reap at his knee/ankle to gain a tactical advantage.
I am sure you realised that the above are nothing magical nor extra ordinary, just basic logic.
To achieve those pretty breakfalls takes cooperation between uke and shite. I view them as just exercise to learn the technique. In reality, it is impossible to do a pretty breakfall, if neither shite or uke refuse uke to do it. Hence my view is that It has less to do with body positioning, more with mindset, depending whether you wish to be aiki (harmony) or jutsu (martial)