A: These pillows are meant to provide a relative humidity of 70%. But there are some factors that could change that level. Each pillow humidifies between 10 and 20 cigars, so 3-5 pillows for a 50-capacity humidor. If you use less, the humidity will struggle to reach the appropriate level. Additionally, the humidity level outside the humidor matters too. Dryer climates will need more pillows, more humid climates may need less. My personal advice: if you're throwing a few cigars in a ziploc or travel case for short term storage (less than 2 weeks), one pillow will work great. If you're looking for long term storage in a cedar-lined humidor, grab a hygrometer to ensure you're at the correct humidity.
A: The Pillows are ideal for humidifying up to 20 cigars. Depending on the size of your humidor, I would say 1 should be good. Maybe 2 if it's larger. You can always take one out, or add one as you need it. Each one tends to last around 3 weeks. You can reuse them several times before you should throw them away. You'll know it's time to get rid of it when it no longer swells to a puffy pouch (starts to lay flat). These are great for traveling and when you may not have a humidor (storing in a ziploc or temporary container). Long term I would say you're better off investing in a smaller jar of crystals. It will cost you less over time, and won't require as much maintenance. Check out the CI Crystal Gel Humidity Bead Jar. This should do the trick.