1. Don't do wallpaper in the kitchen.
2. Simply White does not look yellow. It's a very neutral white. If you want to go a bit brighter, pick Chantilly Lace. White Dove goes too gray, IMO.
3. Whatever you paint the trim, paint the same color on the ceiling. Trim should be semi-gloss, ceilings should be flat.

I don't want to complicate things for you, but I don't think you necessarily have to have the same trim color everywhere. You don't want to have five different trim colors, but if the light is dramatically different in one room you can do something different there as long as there is a good way to cut off between the two colors such that no one will notice (doorway). I have Simply White trim almost everywhere in my house, but I have a living room with a large south facing window where I am going to do White Dove. Everything is brighter and more yellow with strong southern light. I need to calm it down in that room. The average person is never going to notice the difference from room to room. If anything, by using two different colors because of the difference in the lighting they will probably look more alike than if I used Simply White in that room. So if Simply White works almost everywhere, use it where it works and something else where it doesn't work.

Your kitchen is beautiful. It's very similar to the kitchen I had in my previous house, which was also an older colonial with lower ceilings. I painted the kitchen BM Camouflage, which is green (it looks greener in person than it does on the chip). So maybe consider a different color for your kitchen instead of torturing yourself over getting whites to match. The idea of the wallpaper is good, but it seems to be making things more difficult.

I belive that walls and ceilings should be flat. I have found that flat paint gives a LOT of depth. The eye has no sheen on which to focus.

I have no experience with your selections look into Kelly Moore Swiss Coffee 23. It is a soft bright white and we used it and love it. No weird undertones.

The reason the White Dove sample is looking gray is that you have it against very yellow colors. In my house BM White Dove looks yellow on the walls against the BM Chantilly Lace on the trim/doors/ceilings.

@Sabrina Alfin Interiors is right about ceiling and crown molding being the same color. We did it in our house and every single person thought we had raised ceilings, including us! Semi-gloss moldings, flat ceiling in the same color!

First of all, your kitchen is absolutely beautiful, and from the looks of it, so is the rest of the house, so congratulations on your new home!!!

If you're going to do wallpaper in the kitchen, go for something more dramatic than a white or gray miniprint. Kitchens don't have too many plain walls, so you can afford to do something more interesting--perhaps a historical print like a Jacobean or hand-painted floral. Check out Schumacher and Thibaut for beautiful wallpapers.

Choosing between various whites is very tricky because they can look different in different rooms/houses and in different lighting conditions. Both White Dove and Simply White are in the yellow hue family so it's possible that either of them can look yellow-ish. I happen to think that yellowish whites look great in colonial homes so I wouldn't think it's a problem. In fact I tried White Dove in my colonial home and it was way too stark and white, and I went with my tried and true Linen White. However, in my sunporch White Dove looks warm and inviting. Go figure.

In your photo, white dove looks much grayer, but it's possible that it does not look like that in person. The only way you can really tell how a color will look is to test out a large sample in your room and view it at different times of the day and night. Personally I think that either color will be fine in your house, and you don't have to use the exact same color throughout the house if you don't like the way it appears in a particular room.