Skip the packing peanuts - they don't improve drainage and they are a bear to deal with when it comes time to replant your containers. And you need the depth for the bulbs themselves. The reduced weight is not that much of a issue with small planters like window boxes.

If you can find it, bulb planting mix is ideal. Otherwise, any very freely draining, good quality potting soil with lots of perlite or pumice incorporated will work. You can choose whatever bulbs you like, but if you layer different types will you get a much longer season of bloom. Plant the largest bulbs (narcissus, tulips) low in the container, add soil and plant some intermediate sized bulbs (hyacinths) and top off with small early bulbs like crocus or grape hyacinths. If you containers are not very deep (8" is about as shallow as I'd recommend), stick to smaller bulbs including the smaller species type narcissus, like 'Tete a Tete', 'Jack Snipe', 'Thalia', etc.

An unheated garage is an excellent place to store these over winter as long as it doesn't get too cold. Somewhere right above freezing is ideal. Start bringing out into the light in late winter/early spring (Feb/March) and they should start producing green shoots immediately. You may get some early shooting developing in the garage - this may be because temperatures inside are not cold enough. Be careful transitioning these to the outdoors.

You want to water at planting time just enough to thoroughly moisten the potting soil. You may not need to do any more watering during the winter, as evaporation will be very low but avoid letting the soil dry out completely. Since fresh bulbs are self-contained plants with everything necessary to produce flowers already present, they do not require extra fertilizer, but a small amount of slow release bulb fert applied as the foliage begins to emerge will not hurt.

Thanks so much, gardengal! Your reply has been extremely helpful. I am off to the nursery now to pick out my bulbs and soil. I am so excited!
Thanks again!!