For cape code I usually think double hung windows instead of casement and would put these in the upstairs windows. Down stairs consider a bay window. They're usually three windows with the flanking windows opening, but cost maybe an issue,. We have a three panel window with the center window a picture window without grills and the two flanking windows double hung with grills. Our previous window had grills in the center picture window and it is much better without the grills.

Yes, you need double hungs. The large window could hopefully, depending on size be replaced with two or three double hungs. It will look so much better! Cute house, too!

Definitely add muntins to the windows. Do a quick sketch over a printed picture to see if casements with muntins will work proportionally. Same for double hung. Either style is okay, but you need. the muntins to add interest.

Bottom center could remain fixed, but with muntins as well.

I would use double hung with divided lights (muntins) on the the dormers. be sure to try to pick a window that has realistic muntins. I'm somewhat of a purist. I tend not to like the muntins that I see in most vinyl windows. If it is in your budget, I would look at Pella architectural wood windows. they have a very nice divided light.

for the three window unit on the ground floor, I would use divided lights and the size of the divided lights should match the size of the divided lights in the dormers. if you plan to use window treatments on the side windows of the three window unit, the you need to consider how the crank of casement window might affect the window treatments that select.

I assume that you will be using new windows and using replacement windows.

Thanks all for your input. I'm totally new to this. Muntins are the same things as grills, correct? Just different terminology?

Yes, we are going with new windows using replacement windows. The previous owner replaced the back windows on the house with Andersen replacements (400 series). I think that is likely what we will use for the front, too, in order to be consistent. The previous owner put casements on the back windows with the grills. It looks decent, but I have a spouse who prefers the plain glass windows with no grills. I think it looks bare/spartan without.

Same thing. Terminology depends on who you talk to.