I'm not a complete noob to 3D/Maya, but now I'm stuck and just cannot figure out what's going on. It's a face modeling which I would like to print out later.
Right now the faces are going crazy, let me explain.

I try to fix this hole (border selected, shown in orange) - Mesh -> Fill Hole does not work. Append to Polygon also does not work (cannot select the edge), also I have no experience with this tool, because normally I do it as follows and it worked well up to now:
Use Interactive Split Tool to put vertices on the single edge (left, red dot shows vertex-position) where I want the vertices from the edges to the hole's right side to merge to. I just click once and press enter to put a single vertex there.

I do this a second time.

I then select those 3 edges on the hole's right side and pull them out (note the circle-selector set to "world" if I am not mistaken). Oh, what's that, a black face? This normally does not happen, but alright, let's just flip the Normal around (normals -> reverse) on this face.

Looks alright now.

Merge the vertices accordingly (merge to target vertex), showing only step 1:

Moving one of the edges up and down, it shows strange black shapes, I guess because the face is not planar, but I do not know.

Because I had some problems with black faces trying around with this model and am unsure about whether there are double edges, vertices, faces because I did a lot of the "extrude edge to create new face"-method shown above, I want Maya to do a cleanup.

Afterwards the polys start flickering black all over the place.

Deleting some of them it shows: there are now double faces underneath (or rather in the same coordinates) but with flipped normals (because they show black).
Deleting the 3 freshly created faces just makes a hole, there are no doubles.

Another face has its twin there, but it has the same normal (edges in orange; face was deleted, same face
underneath).

Also Booleans do not work, which might account for "there's a problem indeed".
Can someone help? Why are these issues appearing and is there a better method for creating new quad-faces?
Kind regards,
borlag