Can they be washed in the washer?

Yes, but be sure you let them air-dry rather than putting them in a dryer.

Do these water shoes cut into the backs of your ankles?

These water shoes do not cut into any part of your ankles. They are comfortable all around, and be able to tighten and loosen as needed.

Is the sole made of EVA foam or rubber?

The outsole is made of EVA and rubber. The sole is pliable but very strong.

Could you hike in these shoes or are they only durable enough for swimming?

You can wear them for light hiking on smooth trails. If you are heading to a high and steep mountain, we will recommend that you wear professional hiking boots to provide adequate support. You can carry this pair of water shoes as a supplement for hiking. You can take off your heavy boots and put them on when you rest at the destination. The unique lightweight and breathability will let you relax instantly. And they can help you explore the hidden waterfall or stream freely. It can provide traction on slippery stones and protects your feet from sharp stones.

Do the soles come out when wet as you walk or pull your foot out? Had a pair that would do that? Hated it.

No, they don't come out. They're great, and come off and on quickly without any issues.