DeCon in the attic is the way to go. They will smell for a few days after they perish, but the smell will go away (usually takes longer in the winter when house is shut up.)
You said you have a basement, does it cover the whole house, or is there a crawl space that will have vents in the foundation, close to the ground? If you have any of these vents, look closely at them. They have a screen behind the shutter. Make sure there isn't a hole in one of them.
The noise you are hearing in the attic is probably the mice crawling and chewing on the sheetrock. DeCon now! They will eventually eat through the sheetrock, but it will take a mouse a pretty good while to do it.
They are also separating the insulation from the sheetrock when they crawl between the two, which can leave air spaces, cutting down on your insulation R value.
Here is a funny (but true) story from my past.
We lived in a rental house that was at least 25 years old and this was in the mid 70's. No insulation at all in the attic.
Momma kept complaining about hearing scratching noises in the living room. We just laughed and told her she was hearing things.
Then one day while we were all watching TV, sheetrock dust fell from the ceiling next to the front door, and a hole appeared in the ceiling.
A hole about the size of a half dollar coin.
We all got up and walked closer to it, and suddenly a snout with teeth stuck through. It was a squirrel!
We grabbed some wasp spray and sprayed his nose the next time he stuck it through the hole. You could hear him running like crazy across the ceiling.
Next day we set out some decon in the attic, dont know if it works for squirrels but what the hey?
I also went up in the attic and two squirrels were in the corner but ran when I shined the flashlight on them.
They ran out through a piece of siding that was loose, but was hard to see from outside.
We patched the siding and the hole in the sheetrock and that was an end to that adventure.
We still had the occasional mouse, but the decon usually took care of them after a day or two.
Now rats are something that I cannot and will not live with. Even if it means moving.
But all animals are wanting in your house where it is safe from predators and the environment.
You have to find where they are coming in, fix it, then set poison or traps or both.
BTW, the dishwasher: I have installed several of these in my lifetime, and we used to bore a hole in the floor in the back of the dishwasher for the wire (usually 12/2 W ground romex cable) to come up from the crawlspace or basement to power the dishwasher. If you can get to it from the basement, check to see if there is any caulking around the cable, if not put some silicone caulking around it to stop up an entry point to under your dishwasher. If the supply and drain water lines come through the floor, check those too. Might want to check water lines to your sinks too.