Nice house and lot. Storm doors are practical to reduce heat exchange in really hot and/or cold weather -- would not remove it. Might consider removing that row of small shrubs immediately in front of the porch that is alongside the sidewalk in order to make your sidewalk more prominent and inviting, perhaps enhancing the sidewalk itself by outlining it.. Perhaps you could move those shrubs to the side or back boundary of the property.

I think it would look good stained with the blue. It would be a complement (orangish). Red would add a patriotic note with the white trim and blue siding. I wouldn’t go too deep, though. Just a red red. A pale yellow would be pretty. Paint is easier to maintain, especially if there is sun on it most of the day. It is covered, so water probably wouldn’t bother it much. I stained my front door and finished with tung oil. It faces east, so it gets some sun. It has held up well with minimal upkeep. If you used something stronger than tung oil you’d probably be fine for several years.

This is Crisp Romaine. I think it will look great with your shingle color.

I'm going to suggest white for the garage door regardless of the elevation changes that you make. Garage doors should match the body of the house when they are this prominent. Painting them the same color as the house will help reduce it's impact. My second suggestion is to select copper gutters and downspouts. It will frame the home.