So are you saying that this forum should only be used for easy and unchallenging discussions, or perhaps you're just trying to suggest something you find more useful to me?
I think what AndaBien is wondering is if this discussion is helpful for you and your dance - talking about tango in this way, and the perspectives everybody is providing is in some ways completely seperate from being able to dance anything. The true tango exists only at the milonga, what we do here and in practice is practice and exploration of "stuff" that will in the end contribute to our tango.
In the indonesian martial arts there is the concept that it is impossible to teach martial arts, and that what happens in combat is completely personal and individual and spontaneous, the flower (kembang). All that training and teaching and practice provides is the seeds that grow into this flower.
So when i start to think of crosses as sidesteps to the "wrong" side, or as overleading a collection so that the follower is forced to collect on the other side of her original balancing point then these are very incomplete models, and while these models are completely incompatible with other models of what a cross is, they are all descriptions of the same underlying gestalt. They are also all completely wrong and useful only in the sense that each of these models helps troubleshooting a specific aspect of the movement, and allows to play with that aspect of the movement and to expand our vocabulary into a set of related movements that share this concept when we spend a few hours in a practica or renting a dancefloor and playing with this.
So i think the best discussions on this board are either troubleshooting a specific problem (i want X and my follower does Y, and i tried changing a,b, and c, and i have no idea what else i could look at), and having a pool of lots of contributer with unique and contradictory perspectives helps, or they are sweeping more abstract discussions that (again due to the contradictory perspectives) help to spark ideas to be explored in our personal practice.
This thread is sitting uneasily in the middle - it veers from the extremely general (like e.g. i don't think my descriptions of a cross is useful to anybody who doesn't already know how to lead one - (i still think they are useful ideas to play with)) to concrete descriptions of how and where to step, and these descriptions are equally incomplete, because they only describe one part of the puzzle and can only become more concretized when tried with a partner and her movement, not the theory determines what needs to be debugged. So subleties like timing and so on are best explored hands on, either by a teacher who is there, or (the harder way)with a patient and honest partner.
No written description can offer this level of detail, especially as these details are different depending on how tall the follower and leader are in relationship to each other, how heavy,strong,fast they are in relationship to each other, what their personal movement preferences are and so on.
What you seem to be asking for is a complete, "danceable", description of a movement, and that is really, really difficult (and imo probably impossible). Discussions here can help debug things, and they can offer food for thought to be explored, but they can't actually teach.
I personally think it is completely possible to refine and work on ones tango without a teacher, but only when dancing a lot and practicing with a partner to develop the parts of ones dance that are not milonga-ready yet. That is what i do the most of the time as i feel that the group classess offered here are not adressing what i am looking for at the moment, and privates are too expensive to do as much as i want to.
But (and i might be wrong about AndaBiens reasons) similar to AndaBien i am wondering if you are getting what you need from this thread, because your questions sound like you are trying to completely nail down the theory instead of playing with these ideas with a partner to see what happens. The theories and explanations are all wrong, the people you dance with are the only truth. If you wonder about subtle timing differences the board is the wrong place to start exploring this - exlore it with your partner, note what happens, and then start a thread about your experiences, and what other people have experienced with similar movments (or completely different movements - boards are not good at staying on topic

)
Gssh
P.S. I am not trying to discourage you from this board - it is wonderful place to share and discuss, and we surely need more active discussions, but i am trying to share how and for what i use the board, and what i think it can do, and can't do. Other people with different learning styles or who are better at visualizing things might have different experiences.