that seems in the ballpark. the $600 seems a little steep assuming the mantel is just trimmed out lumber, but not outside the normal range. the $200 credit seems about right as well. our mantel material cost nearly $1000 but it was a big beam that they planed and aged for us. the cost of installing it was about a wash with the credit for the wimpy little leuders stone mantel that came standard ($300). the leuders hearth topper was $150 for the stone alone. I don't know the extra cost of stone and building out the hearth support of masonry. but again, i think your costs are reasonable based on my build.

You've lost me, is your new LP gas "fireplace" the vent-less issue, or is the reference to the old arrangement just for reference? But, sounds like a dirty "jet" in the pilot..something that may be well worth the service call, maybe your LP provider can give you a service visit without a charge. I haven't had NGas for so long and never LP, so I don't know what they'll provide as part you buying energy from them.

It's not bad looking, but that's all a matter of personal taste. You could try a stone enhancer on a scrap piece to see if it brings out the color. As far as the grout goes, you will have to do something as the patch really stands out. Re-grouting is very time consuming as the existing grout has to be ground out first. There are many other choices, from river rock and cultured stone, to a more formal look like polished marble or granite tiles.

I think the sectional is just too bulky for the room.. would it be that bad to leave the TV over the fireplace? what are the actual room dimensions? If you hang the tv on the short wall you need to have a way to watch without straining your neck.. what is the width of the room from fireplace (with the hearth) to the wall? option 1 - get rid of the sectional (yes it is comfy but bulky) and put a sofa facing fireplace, get 2 swivel chairs (recliners or not) to either face the tv on short wall or swing around and face the 'people' sitting on the sofa and a narrow ottoman for additional seating.. sketch the room on grid paper with as exact dimensions as you can.. option 2 - leave the TV above the fireplace but i would still replace the sectional with a sofa and chairs so you have more walk through space and the ability to move the chairs if you need to.