I think your benchtop material choice really depends on how both you and your husband live and what level of natural wear you are comfortable with showing. Natural wood benchtops to me are very similar to natural stone or stainless steel. The surfaces will naturally age and show use, scratches and imperfections much more than say a caesarstone if it's a high use area but some people love that look and it goes well with an industrial or natural style. My wife and I thought long and hard about it but realised we want the benchtop to look as new and clean each time as possible so opted back for caeserstone (Ocean Foam) which hid small stains and dust :)

Friends have a similar cooker (not sure of brand) where the stove is gas but oven can be either gas or electricity run. It too is terrible and seems to cut out during the cooking period or if used with the stove top running. We have recently put in a 900mm westinghouse cooker WFE916SA and it seems fine so far (roast, cakes, muffins etc.) It has gas stove top and electrical only oven.

In terms of the mantle - it may have been something more fancy previously. We have 3 fireplaces in our little 2x1 - including the one with the stove. Here is a photo of one of them - although it looks like the timber mantle and surrounds have been screwed on at a later date to suit the house rather than being original.

have you considered a pellet heater? If you have a decent supply of pellets locally they are great. They use a lot less fuel, burn smokeless and can be programmed like a aircon. We had one when we lived in tasmania. I loved that the pellets of compressed wood came in bags and I didn;t have to haul or chop wood. Also we could stash it all inside where no one could steal it ( that's a thing there) I could lift and fill the hopper, It burns a couple of pellets at a time and automatically feeds new ones in from a hopper at the back of the fireplace. I also liked we could program it to turn off after we went to bed and to turn on before we all got up in the morning. We would also program it to turn on before we got home. The guy that installed it also suggested installing a simple duct in the lounge roof and a fan to blow the heat into the other end of the house through the roof. we never got around to that though. you have to wait and see where the heat rises and sits.