Cleaning...Nancy did a great tutorial.
http://www.taxidermy.net/forum/index.php/topic,71316.0.html Look at the photos of the feathers. Good indication of when its clean.
Head incision....dont do that. I do every bird like its getting an artificial head. Skin around the bill and take the real head out. Clean, dry, paint, reinstall and glue.
Dawn soap is all you need.
Neck sewing is no different than any other hole. Same thread, same needle.
I found that i couldn'thide a breast incision or head incision enough to make me happy. I started skinning leg to leg and around the bill. No head cut to hide, leg to leg is pretty concealed and found my birds are much better. the leg to leg takes a little getting used to, but once you have it down it's no longer than any other way with better results IMO.