Hello, I'm a fireplace virgin and need some advice!

I'm looking at either a Heatilator Novus 30" (20,000/14,000) or Heat-N-Glo SL550TR (21,000/15,000), with Intellifire (I want the battery backup for heat when the power goes out). Both are about the same size, BTU and efficiency.

My home is a small ranch, about 1000 sq ft. The sunken living room is about 14 x 20 with a 12' vaulted ceiling shared with the 9 x 12 kitchen. There is a ceiling fan in the living room.

My questions are:

1 - Is the sizing correct, or should I go with an even smaller model? I want to be able to sit and watch the fire without having it overheat the space.

2 - I don't plan to add the fireplace fan, the sunken floor (colder air) and ceiling fan should provide good circulation. Is this right?

3 - Is the optional refractory just for looks, or does it add to efficiency, or length of life of the unit? Just seems like another part that needs to be maintained/periodically replaced and better left off.

4 - The vent can be installed either horizontally or vertically. Is one more desireable/efficient than the other?

5 - The fireplace slides into its framed space from the front. Is access to the side via a panel or door needed for servicing? Or would the fireplace be pulled out again?

6 - I'm on a budget and tempted by the Heatilator over the HnG. What are the differences? Will one last longer, be less expensive to maintain, etc?

Thanks in advance for your help.