If pollen is stored securely in the fridge, how long is it viable? Is it better to let it dry out in the fridge, or protect it from drying out?
Pollen should be stored in airtight vials or containers in the refrigerator, and according to Veronica Read's book, it will last about 5 months, or thereabouts.
The pollen should be stored in either gelcaps, or plastic or glass vials, and a desiccant should be used to absorb moisture. Desiccant can usually be obtained at a craft store, and you should be able to locate gelcaps or vials there, too.
Pollen can also be frozen, if you want to store it longer. It's important to let the pollen and desiccant filled vials sit at room temperature for 24 hours prior to freezing, to allow any moisture from the pollen to be absorbed by the desiccant. Replace the moisture laden desiccant with fresh before freezing.
Keep an eye on the desiccant... you'll want to exchange it for fresh desiccant as it absorbs moisture and changes color.
I had pollen from spring 2007 pollinate flowers in spring 2008 and I have nice seedlings. I store my pollen in clean pill vials.