Yes, you just have to pull the statue off the base and it stands quite well on it's own.
I don't prefer the ACI Aragorn over the Asmus, I have 3 Aragorn from Asmus and they look very good. I like both.
I didn't have a chance to see the Asmus Gandalf the white for real, but the Viper custom is incredible, and for me beats the Asmus version on every point. Not that the Asmus is bad, far from that, but the tailoring and the materials used on the Viper are gorgeous, the robes really look luxurious. And the head is even better than the Asmus for me.