1. For the sake of plot and not having 12 chapters of everyone sitting around kicking rocks, yes.Actually its possible he can activate tomes at will
1. His power "returned exactly when everyone ready to leave", what a coincident
2. Chapter 700 sasuke has no tomes after he recovered
2. Chapter 700 doesn't show Sasuke's Rinnegan.
Tomoe disappeared because his eye wasn't at full power. Now that his power returned, so did the tomoe. Pretty simple.