Metric / Imperial Notes

I'm a bit confused over the whole metric / imperial issue.

What should users look out for when using Metric (bugs, issues, incorrect data in recognition manual, stadimeter etc).

What should users look out for when using Imperial (bugs, issues, incorrect data in recognition manual, stadimeter etc).

I ask because i've read that the torpedo depth is always in meters, the stadimeter is always in meters and the ship lengths are a bit screwed in the recognition manual. I may have this wrong though, hence the post!