Please help this layman understand the supposed expansion of space time. Are all items, even atoms, expanding? Or simply the distance between things?
Supplementary: if my kitchen really is expanding, how might one measure it in theory?
My understanding is that the molecular bonds prevent your kitchen from spreading apart and the new space simply moves around them. In the Big Rip theory, where the expansion, and thus the ‘expansion pressure’ continue to increase, eventually the force will be too great for the molecular bonds to hold and yes your kitchen will rip itself apart, further into it the atoms will also.
From a fellow layman; only space itself is expanding. The stuff in that space is not expanding. The further away things are, the more apparent the expansion is. Closer together, like on the solar system’s scale, gravity is strong enough that it prevents things from moving further apart as a result of the expansion of space.
Technically, the space in your kitchen is expanding. It’s just that the bonds between atoms/protons/whatever are pulling all the stuff back together again. Normally you’d just describe that as being held in place, though.
How could we test if the former were true? We’d have no reference.
Okay, this might be getting into tricky territory, but how can we tell that space is expanding when the matter taking up that space is not separating but is ‘held in place’? I understand how you can say that space is expanding on an intergalactic (intercluster?) level, that it’s not one galactic cluster remaining still and the others flying away from it in all directions, but my brain boggles a bit when you say that the same effect applies to situations where gravity or other forces are holding things together.
We can’t tell. But it is more absurd if space is expanding on an intergalactic level and not on the local.
The expansion of the universe appears to happen at a rate of 73.8 ± 2.4 (km/s)/Mpc. (pc stands for parsec and is a distance of about 3.1*10^13 km)
That means the diameter of the solar system (the orbit of Uranus) would expand by .00000015 m/s if gravity didn’t counteract it. That’s one onehundrebillionth per year.
Now we can’t measure that, but how would space know only to expand between galaxies and not just anywhere?
If your kitchen is expanding, so is the tape measure you’d use to check its size, and so are you, so everything is still going to fit together like it always did anyway. So you can’t measure it but it doesn’t matter.
But, I’d assume, the speed of light would not be changing, so that could be a reference point that you could measure any theoretical change against.
Probably so. Now all you need is something to measure the difference in its travel time from one end of the kitchen to the other before and after the expansion. 
To paraphrase my favorite quote on this topic (from an ancient SDMB thread): “The Universe is full of stars. Does that mean that there are stars in my kitchen?”
I thought about this one day and determined that, the expansion of space could be at a wave length larger than the Solar System but smaller than a Galaxy.
Anything smaller than a galaxy, space would just slip right on by.
But, I’m not a Physicist. 
I had this discussion about a month ago, while walking back to the office from lunch. I wondered if the walk back was longer than the walk there, based on expansion. I decided probably not, as discussed above - locally the expansion isn’t really happening.
But my other questions was if the expansion of the universe is linear. Although I’m not sure if the question actually makes sense…
-D/a
Depending on what you mean by that, the answer is yes, sort of, or no. Roughly speaking, if you plot the rate of expansion versus distance, you’ll get a straight line (the slope of this line is Hubble’s parameter). That is to say, a galaxy that’s twice as far away is receding twice as quickly. If you go out to very extreme distances, though, you’ll find that the plot deviates somewhat from a straight line, because at extreme distances, you’re seeing those galaxies as they were long in the past, and the expansion rate isn’t constant with time. And if you plot the expansion rate as a function of time, you’ll find that it’s approximately an exponential curve, and it’s getting closer to an exponential as time goes on.
Thanks all. So the answer is no… but maybe.
I think you may need to just toughen up and pay for the remodeling if you want an island.