I'll be short. [img]smile.gif[/img]
Nope, the wand isn't necessary to finish the game. You'd just get some extra items ... One of them is a ring I think.
Problems with Imoen... Are you sure you had her memorise some spells? And you should also remember that she can't cast spells when she's wearing armour.
Druids learn spells as they progress in levels (I think). That means they can't learn spells from scrolls. You might find some scrolls for druids (usually 'Heal wounds' scrolls), but you won't be able to learn them - just cast them.
One more thing about scrolls... When you pick up scrolls read them and 'write' them down. If you do that they should be in your spell book.
If none of this help, then I don't know what's wrong.
Oh, and if you have problems with the game, it is useful to play the Tutorial. And the manual helps a lot too.
Hope I helped at least a bit. [img]smile.gif[/img]