Most refurbished computers won't come with a warranty because they aren't being released from the factory. If you're lucky, you may be able to get a refurbished computer that will still have its warranty because it hasn't ran out yet.
That depend on several factors: who refurbished it, how old the system is, and what price you're willing to pay for that system. Most factory refurbished units that have a warranty are great deals...
A refurbished computer can be as good as a brand new computer if a comparable warranty can be offered. Companies such as Dell will replace an entire operating system before putting a refurbished...
Yes, I would say so. They are usually returned for a small defect that is easily fixed and put at the back of the shelves with a significantly smaller price tag.
I bought a refurbished iMac 20"...