Inner tube sizing

Go with the larger. The 25/32 tube will be thinner when inflated to fill a 32 tire but not the 32/47.

You'll want the 25-32. I have 25mm tyres and use the 18-25 size. The 25-32 are too big.

For what it's worth (given that you've made your decision) I have the larger tubes and use 36 mm CX tyres in the winter and 28 mm slicks in the summer without any problems at all.

Usually not a problem using a narrower tube,  but if you patch a puncture on it then besr in mind that you're asking the tube to do even more stretching around the solid patch. Also, you "may" be more susceptible to punctures the more you inflate the tube, think about popping a balloon with a pin when it's full of air compared to one half deflated. This is why tubulars are less prone to flatting, the inner tube is essentially the same size as the tyre, which also leads to a less rigid inner tube and more comfortable ride

Have you ever inflated an inner tube not in a tyre?

I dont see why a smaller inner tube would fail to fill a tyre larger than it's recommended size, I think you are worrying about nothing.

If your frame can take larger tyres, and you could be thinking of eventually getting fatter rubber, go for the larger size.  If the only possibility is for going thinner or staying the same, get the narrower ones.

The smaller tubes probably are slightly lighter, don't know how important that is to you.