Not starting from the center is normal, but not ideal. It makes it difficult to lift the combs out for inspection. You could leave them alone, and hope they build wider and wider combs, so eventually some combs will be on the center. Then next season, cull out the off-center ones. You'll likely have way more than 3. Or you could take care of this right away; cut the combs off and center them properly. Whatever you're comfortable with.
Not building from the entrance is normal, too. It's safer for the brood. They'll make it to the front eventually. Right now you're girls are focussing on getting the nursery set up. They'll pay attention to building the pantry as soon as they can. (It's common for the first 2-3 bars to be used for nectar.)
I don't know what you mean by spacers. What are they for?