Very common for clothes to be ripped/pulled off in water deaths. I wouldn't read much into them not answering that or the trauma question. We need to remember that this is a little boy, not entertainment.
I'm sorry for the image this conjures up, but if he was going through something akin to whitewater, then his little body could have quite a few post-mortem injuries that the ME will have to separate from any possible perimortem injuries