There is room..... 2 x AAA cell sized room. Plus if I remove the flash I could mount it where the flash goes.
The waterproofness for the main unit is not an issue. I have made plenty of dive lights / cannister lights. That part of it is 50% complete+.
When I said IR I mean buliding a reciever to trigger the camera via the USB not via any built in IR reciever ( which it does not have).