Yes, making it a Cryptic Command kind of card is a good idea. Then we can forget about the whole Tome thing/flavourtext because Anusien raises a good point: Elspeth wouldn't create an artifact book to bash other colors with unfamiliair magic tricks.

seems pretty fair for what the card is capable of. When I'm looking at Cryptic Command an an example most of the available options the card provide cost

(Counterspell and Boomerang). Drawing a card costs one (or rather 1/2 of

when looking at cards like Ponder, Serum Visions and Sleight of Hand). Finally, tapping down all creatures should cost about


I guess.
With that in mind I think it's fair to raise the powerlevel a little bit. I think shooting 3 damage to an attacking or blocking creature is fair as many white cards can even remove attacking or blocking creatures from the game for 1 mana (straight up destroying is an option too but I'd prefer the ''red'' in this ability). The Rampant Growth searching up Plains is a great idea. Unearth is fine. I think the last ability could be more ''blue'' so let's give it the Burst of Energy ability. Tap or untap target permanent. It's very Twiddly but white has proven it can do those tricks as well.
Finally I'd like to add that the initial idea of making it so expenise is that I wanted to make sure it's caster would pay extra mana as some kind of fine (in lack of better words) seeing that being able to shock a player with a white card is fun but completely unfair. Other than that, I didn't want to make the mistake of creating a card that is out of flavour as well as powerful. That would make it a little over the top, or just lame.
That being said, I completely agree with the new ideas. The card is not only much better, but also more fun.
I picture the art being the same as the Command cycle, where magic escapes a jar and flows into four different directions. The colors blue, black, green and red should be a little visible in the different streams so that the idea behind the card is visible in it's artwork.
EDIT: Burst of Energy doesn't tap, so maybe that's no a very good idea. I'm not sure if white is supposed to tap doen lands and stuff.