日本語レッスン08 「と・ば・たら・なら」(1)
Perhaps you will find this useful.
I tried to read your post but honestly I got a little confused. It may be possible you are over thinking the issue.
As for difference between ば and たら, I feel it is a little more simple. They are nearly interchangeable, but not completely. They both illustrate conditional situations, but たら is more... multi-purpose(?). There is a slight difference in their emphasis but it's kind of depending on context.
If you use ば the part that comes after is restricted to fact/direct result that would happen if the first part is true.
If you use たら there is not this kind of restriction. The part following たら can be a request, opinion, command etc.