Nut low in hi-lo regular?

[7n7]

What is it?

I'm having some trouble finding this information. SSI doesn't say and I'm not having much luck with google.

Is A high in this game?
A2345 counts as straight and only an A-high low (rather than 5-high)?

Also, in SSI, Sklansky says 345 is the best starting hand. If A is high, why isn't 234 the best? More high potential with the 345?

Thanks!