Beautiful! It looks very similar to the Cora Louise, except the Cora has more yellow in the center. If I can squeeze one more Peony into my garden I am definitely getting a Raggedy Ann.

Your going to need plans to submit for your building permit more than likely with an engineers stamp or architect so that may be a good place to start as you will be changing or altering the structure (roof and roof loads) of your home. And generally this would all be done in conjunction with the framing for the porch.

Here's a photo from our walk-through with the previous owner's stuff 5 years ago, though you can't quite see the notched part where the cabinets are set into the window trim. It's not the same situation since our cabinets are on the window wall, but I think the filler strip option would work nicely in your situation. I wish ours had some separation rather than notched-out trim - I think it might have happened when they replaced the windows in the 1990s. Since the cabinets were built on-site, I have a hard time believing this is how the window was originally. I'm glad you brought this up - I never even notice the weird trim with it hidden by curtains. I hadn't given it a lot of thought while working on my IKEA design, so I'll have to look at it again to make sure I eliminate it.

I'll say, it's not ideal but that doesn't mean it won't be just fine if its flashed and finished properly. Fortunately you have a good size eave right above it and because of the roof slopes not much rain will head to that valley. You may get some debris build up but it really just depends on your site and the wind around your house. If you extended the porch roof into the 10/12 roof you would still have a condition that needed to flashed properly to prevent future headaches. The advantage to the location of this valley however is that it appears it is entirely 'outside' so it is not over an interior finished space - and I would much rather have a leaky roof over a porch than a leaky roof over a living room.