(Sorry i'm not sure how to multi-quote so i'm just going to list the names here)
For gnomeman88: I somewhat explained what that meant in one of my posted above, try looking there to see if that helps.
For Manace and Seisai: the explanation I wrote was to explain the reasons for your problems, and maybe anyone else's issues, I hope it helps. Little side note, the helm thing is because everyother race or so has a different headsize and when you switch the look sometimes the head doesn't fit correctly and it will look all crazy so just use interface options to hide the helm.
I'm no genius in this so i'll just try to explain what i've found out about the UD body Human face thing.
I've changed my Draenei so many times that i've noticed a couple of things. When you change your race from x -> y the game uses the skin, textures and I think partial skeleton movements from the race you are turned into to make your character look like the race your want. Too try and make it less confusing i'll give you an example of what I mean.
(I've given two explanations below since some people don't want to read my life story and would rather get right to the point, but it's more written out and might help a few more people understand. Sorry, I like to write :P)
(Written out explanation) I changed nearly every Ally race to Blood Elf ('Cause I love BE ^_^) because my friend refused to go Blood Elf so I wanted to just make myself at least look like one. When I switched all the races to BE I noticed that there were a few differences between them all like a mixed breed of BE with that race. I'm assuming it tries to use that races skeleton and skin too make it look like a BE (or the race you want in this case) so there were height differences between the BE/Humans the BE/NE the real Blood Elf and the BE/Draenei. The BE/humans had hairy ears that somewhat matched the hair color that you pick and they were a bit taller than normal BE and there were a few differences in the bodies like BE-F popped their hip out more. BE/NE actually looked pretty cool IMO, they had a few marking choices that kinda shined off of the BE face and fit into the BE body well seeing as how they are elves also :P BE/Draenei were humorously enough, shorter than the rest and their skeleton was much more loose when you played with them (as in they seemed to more more fluid-like rather than stiff as some of the races you turn into end up) but they had that distinct missing shoe thing that people wondered about was because Draenei's hooves make it so they don't need the feet part of the boots and when switched to BE they just have either bare feet with the rest of the boot showing or a hoof in the shape of a foot. Your best bet is too switch the body before you make the character so that you can look through the list and see what looks a bit awkward and what looks more like you want to know what I mean. If you switch after you'd made a character like if you already have a high level and are not willing to start over you just have to be lucky and get a nice hair/face etc... combo, or try a different race.
(Summary explanation) When you switch from (your race) to (the race you want) I assume the game uses that races skin/texture/skeleton to morph that race into the one you want so there is a few cosmetic differences when you switch. For the best outcome you should switch the race first and than make the character butif you already have a high level and don't want to start over than you're just going to have to hope for the luck of the draw.
If anyone else has any issuses i'm more than welcome to try and help you with them. Just leave a post.