We had a garage door to paint that was powder coated aluminum. The BM guys recommended priming with Stix which we did and then put the finish coat on it....so far so good. Only thing is the stix does dry really quickly so I had to paint it not in the sun and on a fairly cool and humid day for best results.

That's a lovely shade of black. It appears to have some blue or teal to it in the photo, although I have a crummy monitor. Do be careful with black. Often they will become a dark lifeless hole on the face of your home. You might look for some that are not a true black but that have other undertones that go well with your house's coloring. There's a house around here that does have a black, black door and it looks so great on that particular house. Today I passed a really rich brown black on a gold house that looked great. Don't see that color very often.

Good point about the garage doors fading away. When I bought my house they were a contrasting color. Once I painted them the same color as the body of the house, the house seemed much larger. Also, the front porch was more prominent. I think if you do this for your house, then your very lovely front porch will become the focal point. Right now, it competes with the garage doors. So i recommend painting the garage doors a color that is very much like your brick and selecting a color for the front door to make it pop.

There isn't enough room to add shutters to your windows and they wouldn't look right if there were enough room. Here is a brief article on shutters so you see why they won't work on those windows in that location of your home https://www.lifeofanarchitect.com/residential-architecture-101-shutters/ Also, the door style you have chosen with the large oval is not appropriate for your home's style. It's a Victorian window (that oval). I know it's seen everywhere, but it just isn't the right style to enhance your home. Are you wanting larger window/lite in your front door? Or are you planning to paint your current door black (a better solution)?