Yes, light weight is critical for many load cases. Its just a matter of defining the flight envelope and working thru them. The important thing is to make it clear to the pilot what the limits are. There are few flight manuals which achieve that objective.
VA is largely up to the designer. VA min is specified (by FAR 23 for example). There are provisions for having VA less than the corner of the flight envelope. On the other hand, the designer may choose a higher VA.
Consider that last point. VAmin is specified as being nominally at the corner of the flight envelope (I say nominally as it ignores dynamic effects on CLmax, cg position etc) yet I can choose a higher VA - and I can choose it to be constant at all weights. I can determine all the appropriate load cases per FAR 23. Clearly, that VA has nothing to do with the stall line - its only related to limitations on control application. Of course, full elevator can take it beyond the limit load factor - hence the term "checked maneuver" in those load cases.