how would i work out wingspan and suface area from a bodyweight?

Of what? Are you trying to work out the wings needed to lift something of a given weight?

 

You also need to know velocity - lift increases with velocity squared, so you need much bigger wings for slow flight than for fast.

yea i wus tryin to work dat out

 

how would you work out an efficiant velocity then???

It depends on your propulsion - flapping flight, propeller, jet, rocket?

flapping

For birds, the generally accepted limit of wing loading is 25 kg/m2, but most of the truly huge birds have a loading of about 15 kg/m2.

so for a 30kg bird it would need 2 m2

Yep.

ok thanks, any idea of energy requirement equations???

For birds, just google "birds" and "net cost of transport", but be aware that biological organisms are far more economical than anything we can build.