I used white dove, a very popular white, for my kitchen trim and I think I used super white in my living room and dining rooms. They are all separate rooms so the colors are not seen against each other. I really like the collingwood, but I don't like the super white with the cloud cover. If it were me, I'd pick one white for the trim and the cabinets. Have you considered white dove?Or cloud white?Consider satin for your trim instead of semi-gloss. It gives up the same durable washable surface with less sheen. Also matte finish for the walls, more washable than flat. Flat is ok for ceilings.

Yes absolutely. My main house is beige. Both my bathrooms and laundry room are dark bold colors. I really like it that way. Bathroom 1 BM Van Deusen Blue, bath 2 BM Moroccan Red, laundry room BM Caponata (deep raisin plum - almost looks black certain times of day.) All the rooms are small and I think they all look more interesting and the laundry room especially, looks larger.

That's a beautiful color palette! There is a way to do a "design seed" using any art, but I can't remember the site.

It does look very nice! I think any of those more traditional/transitional patters will work. If you want to stay with a neutral pallet I would focus on lots of texture and making sure whatever you decide on has the same undertones of your paint choices. If you do want to bring in color bring in maybe one color but several different tones of it. Emily Henerson has a great blog post on designing with neutrals https://stylebyemilyhenderson.com/blog/how-to-decorate-with-neutrals-beige and Maria Killam's blog is dedicated to understanding color theory to make sure all your colors are harmonious, especially when it comes to neutrals. She also has a more traditional style and uses examples of that in many of her posts. https://www.mariakillam.com/blog/ You really have a blank canvas which you can do so much with! Any inspirational images you have that would point us to your sense of style would really help to source specific things.