Best oscilator scheme for watch crystal
You don't say what the device this is going into.  However, if there will be a micrcocontroller present then you likely don't need a separate crystal driver at all.  Many microcontrollers (and just about all Microchip PICs) come with low power watch crystal oscillators.  You add the crystal and two caps, and the micro does the rest.

Yes, driving the crystal with a sine wave is the best for the crystal.