I'm planning on getting Dawnguard soon however I'm wondering does it affect the appearance of all vampires?

What I mean is when my character becomes a vampire in vanilla skyrim their eyes change color and the shape of their face changes a little i.e. chin becomes more pointy eyes become less deep etc.

When I install dawnguard will these changes be different and will the appearance of all vampires become updated?

I have heard that dawnguard vampires faces don't change shape their eyes simply change color, is this true?

The reason I'm asking is because now whenever my Dark Elf becomes a vampire and does his angry face during battle his eyeballs glitch and clip through his face which is annoying.

Yeah, the player character's eye colour changes and skin colour changes slightly too. If you're on PC, you can use the showracemenu console command to give yourself the 'bat' like vampire appearance. All existing vampires in the game will have an updated appearance, with the new eyes etc. Most enemy vampire's and some NPC vampire faces change to http://www.uesp.net/wiki/File:SR-npc-Rargal_Thrallmaster.jpg.

I didn't like the face changes at all, so I edited the dds files.

I'm unfortunately on PS3 but I've heard Dawnguard is close. It's mainly the facial shape changes in Vanilla skyrim that cause this glitch for me and I was hoping dawnguard would fix that

No idea, I don't have a dark elf vamp, and none of the ones I've encountered had any eye clipping.

That's strange. Will the player change to look something like that too if they are a vampire?