For practical construction reasons the chimneys will either both be masonry with clay tile liners or all double-walled metal. Combining metal and masonry chimneys would be pointless. The fireplace in the photo is a "zero-clearance" metal fireplace (2" from combustibles) and will be designed to use a double-walled metal chimney most likely made of galvanized steel. If you wish to have a masonry chimney you should also build the fireplace from masonry. You refer to an "insert" and that is an entirely different kind of fireplace, usually a cast metal stove that is inserted into an existing masonry fireplace. That is not what is shown in the photo. What do you mean by a "traditional" hearth? The hearth design is an entirely separate issue but the building code will require some kind of hearth to protect the floor so it is good to decide what you want now so it can be structurally supported. The options are that it can be flush with the floor or raised and it can be larger but not smaller than the code requirements. The photo appears to be a mock-up for a sales brochure since the tile surround and the hearth extensions do not appear to be code compliant. The wall also appears to be some kind of paneling rather than CMU.

Agree with the roof wizard, your roof color is not visible from the pics. If you can provide a pic showing the roof and the whole house, it that would help. Having said that, I think that peachy/beige color on the bottom of your home needs to be a much darker color in the browns to ground your home. The red upper porch conflicts with your stone too. Once a photo of your entire home is provided maybe we can provide proper direction for colors.

What should be the minimum length of the furrings from the wall. A 2x4 probably wouldn't work only because the garage doors are too close to the walls. Would 1" furrings be enough with 3/8 drywall? Would some sort of paint or a form of insulation help? I plan on using foam insulation on the ceilings and will probably do what I can between the walls unless maybe something else is ideal.

Paint all of it the khaki and paint the front door ocean blue. Railings should be a crisp white. Absolutely add foundation beds with local, plants to soften the cinder block. Set the plants in local beach pebbles for a natural look. Add a couple of ocean blue chairs and a little round table on the porch.