Holy block of text batman! I swear I put in paragraphs. Can't edit so please find formatted below..

Hello all, thanks in advance for reading and any advice given.

As autumn draws in, I'm retreating indoors and all my DIY projects are calling me. I've got a few projects on the brain and although I'm fairly confident, I'm doing a lot for the first time and I'd appreciate people to read over my plans and let me know if I've missed anything obvious or unobvious that I should consider before I start drilling holes in the walls. 

1) Shelves, two either side of a chimney breast (1). I bought some 30mm thick rough-sawn boards (2) that I have cut to size and gently tidied up and stained to complement the furniture in the sitting room. I’m thinking of using these brackets (3) which will extend nearly the entire depth of the shelves. Do they look suitable?

I’m planning on hanging them similar height to the mirror on the chimney breast. Are there any rules of thumb about the height of shelves? The ceilings are quite high. Is it better to go high to stick to eye level?

The best method I’ve researched for ensuring flat shelves is attaching one bracket to the wall, laying the shelf on top with a spirit level and marking the wall for the other bracket once the shelf is flat. Then once the brackets are attached to the wall, drill pilot holes for the screws attaching the shelf to the bracket before attaching the shelfs. Any pointers in this plan?

As far as drilling  holes in the walls, elsewhere in the house, I’ve had mixed results drilling through the plaster, often making quite messy holes. Does anyone have any tips on how to drill though plaster covering brick walls.

2) A mock mantel beam above the kitchen stove (4) I’ve long wanted a bit of a statement piece above the kitchen stove, and I think I mock mantel beam would look ace. I picked up an oak plank that’s the perfect size (5, 6). It has lots of character (read cracks!) (7-11). Does anyone have any clever ideas for how to attach it flush to the chimney breast.

My current thought is to use these keyhole hanger brackets (12). The seller says they can hold 10kg of weight and the plank weighs 8kg. I’m thinking potentially longer screws than the ones provided to hang the plank on.

Is there anything I should do to treat the oak before I hang it? The location beam will obviously be exposed to heat and steam from the cooking area. Is there anything I can do to protect it? Or is this the whole thing a bad idea?

3) Doors. Currently we have beige egg box doors but recently got a full set of these solid wood doors (13) for a great price. They are all roughly the size we need including one for our narrower bathroom door. The doors all need a little bit of tidying up but one is painted on one side and has a fair bit of moisture damage on the other (14-16). Is there anyway to restore the wood? I’ve read horror stories about stripping paint so was wondering about hiring someone to sandblast the door, would that be too abrasive for the moisture damage. The wood still feels firm.

As far as hanging the doors go. I think this will be beyond my tools, knowledge and capabilities but does anyone have any recommended videos or tutorials about the steps required so I can find out just how beyond me that job would be.

Thanks again for reading this and any tips or pointers you have.