So for what it is worth, I am with Sophie on this one. You need an architect. My first thought is there is no way this house will support any dormer on the front. I think any dormer that will add meaningful space is going to overpower the house. I really don't see a way to put any dormer on the front of the house without an architectural redo, and honestly that seems a bit like throwing good money after bad. Let me remind you that I am right every time, that I am not wrong. So having said all that, it may just be my failure to visualize your plan and it could end up looking amazing. If it were me and I wanted the room I would add in a large shed dormer across the back of the house. These are pretty acceptable architecturally and they add a lot of meaningful space but they also really elevate the scale of the remodel.

Your inspiration photos seem to solve your needs. A long bench, with drawer or basket storage below and a double hook (possible a shelf) beneath each window, would give you a lot of storage. You may even have room to add a tall, pull out cabinet at each end or you could modify the closet to have a pull out as well as hanging area. You could add ceiling height, deep cabinets over your washer and dryer and a countertop for folding. If you must have a hamper, as in your pictures, buy a decorative one and store it under your window. After that, just add a rug and it would look great.

I think I'd go a little more fancy with the mirror to make this space a little more playful and interesting. I'd say that the smaller size would work better with the console size.

You're still going to have to pay for someone to remove the arch for the transom - I'm wondering if you could have someone frame up an arched shelf so you keep the original arch but close it up for privacy. And, having said that, you could also fill the arch in to accommodate a standard glass panel door and hang an arched decorative piece above to mimic the rest of your arches...