Absolutely! One of the things that I think makes a house a home is that it looks put together over time not all at one shot. One way to get that look is to mix tones of wood. To my eye mixing tones of wood gives a richer more layered and interesting look than when everything is all one color. All of our trim in our downstairs is quarter sawn oak stained very dark but the oak wood floors are stained the lighter orangey color original to the 1908 build.

" am wondering if the grout will appear lighter or darker than the color card after it dries....." Yes it will dry lighter or darker. Color and brand dependent as well as how it is mixed if powder vs premix. I would make up a sample board, as there are to many factors that influence this.

You can go either direction however what is more important is the undertone in which your pieces have. The first set of chairs you have pictured has a very yellow undertone for example and won't work well with your finishes. the second set of chairs have the same tone as your finishes. Where you will really want to be the most aware of is that everything doesn't blend together and that you have contrast. Do you plan to have a rug under the table? That will break it up and you will be able to be more lenient with your wood tone choice.

OK...your cabinet installers will need to know the THICKNESS of the floors so they can adjust the box height. They will need to do this BEFORE the counters are put in...so that dishwashers fit....etc.