The best toothbrush is the one she'll allow you to use on her
! The one you linked to is great though.
I like to use Healthy Mouth additive (VOHC approved) too - I put it on their meals.
I only clean ears during baths, I just use the shampoo etc but I don't clean the inside of their ears with this...just the surface areas.
As far as other things to know - the most inportant thing at this age is that you be VERY careful w/ exposing her to other dogs and germs while she is still getting her puppy shots.