#1 How well will this work for vacuuming carpeted stairs in my house?
Yes. This is better for inside the home than for the car. This also works better than the pet hair eraser hand held. The only difference is the attachments. I use this inside for stairs, pet bed, furniture etc.
#2 Dirt goes inside this Bissel vacuum but it also sits outside around the vacuum. Why is this happening?
My unit does not do that maybe you got a bad seal or something make sure the filter seal is clean before you put it in I clean filter good with a brush may be that why it’s happening
#3 Does this use a charging base or a cord to charge?
The charger is corded. The charger its self is of very low power which means it takes a very long time to recharge---the instructions say it can take 8 hours t bring the vac to a fully charged state.