Is it difficult to open an E-store that is not on-line
An E-store can only be online, hence the name.
I would think so. If you don't have a brick and mortar store and you aren't on-line, where are you going to find customers? How are they going to find you?
Not really, since that's basically not a store or business or anything.
How or where would it exist IF NOT ONLINE ?E-Stores are all online.