I buy several hundred dollars worth of wood at a time from Balsa USA. I've never bought from Lone Star but I've heard they're good.

They select the wood for you so you don't know what you're going to get exactly. That's one of the reasons I order so much. I get a good selection so I can always find a piece that will work.

4-6 pound wood is also called Contest Balsa. You would use it for non critical structural members to save weight. For example, wing ribs or sheeting. You could also use it for formers that don't bear any significant loads such as turtle back formers.

But don't ever use it for spars or longerons. It's not strong enough.

As far as storing it, just lay it flat. Also, if you store it someplace other than your shop, be sure to move what you use into your shop a week or so before you plan to use it so it can be climatized. For example, if you store your wood in an air-conditioned house, but your shop has no climate control, you have to give the wood time to adjust. Otherwise you're asking for warps.