I like all of your Froakie ideas. I've got no expectations for his typing, really. As long as he's dual SOMETHING and has a nice design, I'm sold. All of your suggestions work wonderfully.
As for Chespin, I'm rooting for a Steel, Rock, Ground option. I like Grass/Rock the most as its an awesome type combo (and would fit into my master team). Grass/Ground for the same reason and Grass/Rock BUT is a bit discouraging as we already had a Grass/Ground starter. Grass/Steel is great too because...well, have you SEEN Ferrothorn??