Fine tuning edge and label placement in dot - graphviz

Question

I'm plotting a graph in dot. In order to make it legible I need to fine-tune the placement of the edge labels, as well as (if possible) making certain edges straight while others are curved. I would appreciate general advice on how to accomplish these things in dot, but for the sake of concreteness I include my specific problem below.
Here is the code, followed by what it currently looks like:
digraph myGraph {
rankdir=BT;
splines=line;
"AB.BC" -> "AB.AC.BC" [weight=4]
"AB.BC" -> "ABC" [color=red,style=dashed,label="I(A;C|B)"]
"A.B.C" -> "A.BC" [color=red, label="I(B;C)"]
"A.B.C" -> "AC.B" [color=red, label="I(A;C)"]
"A.B.C" -> "AB.C" [color=red, label="I(A;B)"]
"A.BC" -> "AB.BC" [color=red, label="I(A;B)"]
"A.BC" -> "AC.BC" [color=red, label="I(A;C)"]
"AB.AC.BC" -> "ABC" [weight=4]
"AC.B" -> "AC.BC" [color=red, label="I(B;C)"]
"AC.B" -> "AB.AC" [color=red, label="I(A;B)"]
"AC.BC" -> "AB.AC.BC" [weight=4]
"AC.BC" -> "ABC" [color=red,style=dashed, label="I(A;B|C)"]
"AB.AC" -> "AB.AC.BC" [weight=4]
"AB.AC" -> "ABC" [color=red,style=dashed, label="I(B;C|A)"]
"AB.C" -> "AB.BC" [color=red, label="I(A;B)"]
"AB.C" -> "AB.AC" [color=red, label="I(A;C)"]
}
This is close to what I want, but it has a few problems:
The labels are placed in such a way that you can't easily see which one is associated with which edge
For some reason, some of the edges have a bend in them at the label. (They came out as straight lines before I added the labels.)
I've tried playing with the rowsep and nodesep attributes but wasn't able to improve it. If I remove the splines=line line it becomes legible but isn't really what I want:
It's fine for the dotted edges to be curved -- it's actually good, because it will prevent them from overlapping the second node from the top -- but the solid ones really should be straight.
I'd like any advice on how to fine tune node, edge and label placement (as the documentation is really unhelpful and good examples are hard to find), but specifically, my questions are:
Can I tell dot to make specific edges curved while keeping others straight? (I know there is a splineType edge attribute, but the documentation doesn't give me a clue how to use it and I'm not even sure this is what it does.)
If the above is not possible, how can I tell dot to make the straight lines dead straight, rather than bending at the label?
For straight edges, how can I fine tune the placement of the labels? I don't mind doing it by hand, and there seem to be several edge attributes that should help me do that, but none of them seem to have any effect whatsoever, so I must be doing something wrong.
As a bonus question: is there a way that I can give the nodes a more grid-like layout, so that they're nicely vertically aligned?
Any answer is appreciated, but most especially helpful would be answers that explain how to handle these issues more generally, for the sake of future visitors, rather than just fixing my code.

Answer 1

If you use the neato layout engine, you can set the nodes explicit coordinates with attribute pos="x,y". In dot layout engine this is possible by using {rank=same; node1; node2; ...} for vertical alignment and group attribute (node1[group=g1]; node3[group=g1];) for horizontal alignment.
The position of the labels can be changed using the attributes headlabel and taillabel.
Image:
Script:
digraph myGraph {
layout=neato
splines=true
rankdir=BT
node [pin=true]
"A.B.C" [pos="0,0"]
"AC.B" [pos="0,2"]
"A.BC" [pos="-2,2"]
"AB.C" [pos="2,2"]
"AC.BC" [pos="-2,4"]
"AB.BC" [pos="0,4"]
"AB.AC" [pos="2,4"]
"AB.AC.BC" [pos="0,6"]
"ABC" [pos="0,8"]
"AB.BC" -> "AB.AC.BC"
"AB.BC" -> "ABC" [color=red,style=dashed,taillabel="I(A;C|B)"]
"A.B.C" -> "A.BC" [color=red, label="I(B;C)"]
"A.B.C" -> "AC.B" [color=red, label="I(A;C)"]
"A.B.C" -> "AB.C" [color=red, label="I(A;B)"]
"A.BC" -> "AB.BC" [color=red, taillabel="I(A;B)"]
"A.BC" -> "AC.BC" [color=red, taillabel="I(A;C)"]
"AB.AC.BC" -> "ABC"
"AC.B" -> "AC.BC" [color=red, taillabel="I(B;C)"]
"AC.B" -> "AB.AC" [color=red, taillabel="I(A;B)"]
"AC.BC" -> "AB.AC.BC"
"AC.BC" -> "ABC" [color=red,style=dashed, label="I(A;B|C)"]
"AB.AC" -> "AB.AC.BC"
"AB.AC" -> "ABC" [color=red,style=dashed, label="I(B;C|A)"]
"AB.C" -> "AB.BC" [color=red, taillabel="I(A;B)"]
"AB.C" -> "AB.AC" [color=red, taillabel="I(A;C)"]
}