The DVC section is actually pretty close to the lobby. You do have to kind of walk around to the other side to get to the DCA entrance, but it is all fairly compact. I've never done DW, but from what I've heard, you are going to find that all of Disneyland Resort is super accessible, especially staying at the Grand Californian. To get to Disneyland from the Grand, you go out to Downtown Disney and turn right. When both parks are open (and it's not first thing in the morning), we like to enter California Adventure from the Grand Californian, walk through DCA and then hop to the Disneyland gate. I'm not sure it's shorter, but it feels like it to me and I like the ambiance of the park better than Downtown Disney. We do the same thing in reverse returning to the hotel (assuming there aren't lines getting into DCA). People say not to use the Grand hotel entrance into DCA first thing in the morning, but honestly when we have, the line feels long, but we have always been in the park before opening time. In fact, we are usually about to Toy Story Midnight Mania by opening time, because a CM will start leading a group down there, and a separate group to Carsland.
You are so close to both parks that you don't need any transportation. It's such a sweet location! Enjoy!!