Subject: What is the best way to get an airship to have optimum lift capacity?

With an airship "renaissance" on the horizon, I was wondering whether 
helium-filled is the best way to go. My first question is whether there is 
a certain helium-hydrogen atomic ratio which would practicaly take away 
the hydrogens chances of recreating the Hindenburg disaster or whether any 
amounts of hydrogen is dangerous. Part 2 of my question is, taking into 
consideration all the advances in nanotube/molecular structure technology, 
whether it would be more efficient in terms of lift capacity to have 
almost all the air sucked out of the airship (with traces of helium left), 
or in other words almost a complete vacuum? If so, what would be the ratio 
of lift capacity (vacuum/helium) and would it be stable, because if 
something punctured a hole in it, would the suction cause it to crash? I 
hope I'm not asking an unanswerable question. Thank you.

Re: What is the best way to get an airship to have optimum lift capacity?