Either way will suffice, the important thing is to not leave the inputs floating. Usually you would connect all unused inputs to ground, the only reason to daisy chain them would be if it somehow made the layout easier. Daisy chaining them will cause a slight increase to the current used by the device so you might want to ground the inputs for a battery powered circuit.
It depends on the oscillator topology used. Any inverting logic element can be used to make an oscillator since they inherently provide a 180 degree phase shift. An oscillator is often made from one, two or even three such elements and sometimes another gate is used to buffer the output of the oscillator. In fact, any number of elements could be used to create an oscillator but there is seldom any need to use more than three. An odd number of elements will inherently oscillate where as an even number need to be forced into oscillation usually with enough capacitance to add additional phase shift. Single element oscillators need special care as the feedback resistor will make the element operate in a linear mode and it may or may not oscillate. If it does oscillate it may not be stable. However, the use of a schmitt trigger element prevents this making it a reliable oscillator but it does become sensitive to supply voltage variations as the schmitt trigger thresholds vary with supply voltage.
That was a little more long-winded than I intended but hope it helps.
I found this, it might provide a little more information: