Hmms. Good questions to think on.
On the first one I never seen any of the First 
Tenchi OVA opening. 
Same with the El Hazzard, don't know. Mabye the 
AIC never relased them? Or the ones they 
did put out were snatched up fast.

I've seen alot of Street Figther Cels from the new 
OVA recently In fact I got on of Sakura n.n Got it 
from Yann. Worth every penny IMO.