Sanyo XACTI is by far the smallest and lightest combination with a housing, as the housing smoothly fits to the camcorder. XACTI however is not the best camcorder, unfortunately low-light is one of the weaknesses; you may check into tests, e.g. on slashcam or in magazines - but considering the very low price of the combination, this might be what you need - and it is not bad at all.
I do not know any camcorder/housing which you could attach to the head or whereever else. All housing I have ever seen are for two-hand usage only. If XACTI is still too big for you, stop searching, I’m afraid. Also, 60 m and a very small housing does not work together. 60 m requires a professional housing and those are not small. But below 30 m, nothing works without light, which you also need to carry. Your requirements cannot be fulfilled in total - nowhere. You have to give up something.
Regards, g