Monstrous common mounts?

Under the Mount equipment (commonso available to all classes) is stated that it's possible to upgrade the mount with a single accessible trait and add the extra point cost to the base of 15 points for the common mount. If doing so, however, this requires taking either a faction or class trait that only applies to the mount.

Now, 2 questions:

First, and most easily, assuming my faction builds around earth to gain the sphere bonus of +1 toughness, if taking a faction or class trait -outside- of this sphere (like, say fire), does this negate the +1 toughness for the models, or will they retain it because this new trait applies solely to the mount?

Second, since a normal mount pretty much only provides a movement boost and I want to spice it up a little. Can I take the primal sphere trait 'Twilight Beast' as a class trait to give the mount Monster2, and thus provide it with 2 cool monster traits? Like for example, to giveit claws to attack with. Furthermore, I assume this is only possible after faction creation due to the extra progression cost attached to it?

Thanks in advance!