Yup your 2nd question/point is exactly it. Tidal heating affects the core more so than the crust or surface.

As for the radiation problem, well water is great at filtering out different damaging wavelengths like UV and so on. Also, even besides that, you have extremophiles that can thrive in some of the strangest and harshest conditions. I wouldn’t be too surprised to find something living (even if it goes against my intuition). Hope that helps.

Here’s a great FAQ that will give you more details and the science behind some of the good questions you asked: https://solarsystem.nasa.gov/europa/faq.cfm

I was also wondering about the radiation from solar winds blown back by Jupiter’s magnetic fields. Would that not kill life on the planet or creatures living beneath the surface be sufficiently shield from it?