How odd to put carpet in a fireplace. I would suggest you made a hearth with a piece of stone - sandstone or slate or even tiles maybe - then you can dress it with candles, a pile of logs like Rukmini said, or a fire grate (loads of secondhand ones on eBay) and dress that with logs. I rather like the example below with a cluster of plants. You could also try an electric faux wood burner as minnie101 suggests. They are reasonably cheap (£100-£300) and most have an option to switch the light on without the heat if you so choose. Dimplex is a well known brand.

The pipe in the marble one may be a gas pipe where someone may have had a gas fire inserted there. If it is, then a gas engineer will be able to remove it and seal the end for you. It may be an idea to get all the chimneys swept before you decide to use them for a fire.

I honestly don't think it will be a huge deal to have the fireplace to the side (I'm usually very OCD about having things symetrical) if the fire surround is going also that sortof means it won't be such a huge chunky thing and you could tone it down.. of you brought a wood burner you could get one of those long tall ones and then almost turn that corner into the 'cosy' area- I'm afraid I don't have an image of this but my friend has done it and it looks really good you can still have the sofas boardering the room the whole way round but just have the log burner in the corner

I don't think the wooden surround is original to the tiles (though both could be unoriginal to the house) The black one would look good with a nice metallic paint like bronze and ditching the wood beading round the edge. Or kept in a matt black and dry brushed with a metallic paint to pick out the detail The tile one needs either a) completely removing if you don't like it b) painting the surround and maybe adding a little touch of 1/4 round beading to try and harmonise it with the tiles c) a new surround to match the tiles.