Hi Basil, I use Manual Focus 90% of the time except when I was experimenting. I use "Back button focus" technique to pre-focus before I start recording, after that I just rely on the focus peaking to move my camera and follow the creature to make sure they stay in focus. When I tried the LX100 on land, I was very concern about over expose as well. I tried it around Dec/Jan when we have snow here in Kansas City area. I tried to get the nice blue color sky but the cloud and the snow were way over expose, so I thought I need an ND filter. But once in the water, the problem goes away although you do have to pay attention to white color subject. For the LX100, the sharpest is at F4 or F5.6, so use the lower ISO possible before messing with higher Aperture. Also, when shooting in the water, try not to go above ISO800 for wide angle shot otherwise you the noise is quite bad when you blue water background as part of the composition.Hope that help!
Thanks for the info! It's good to know you did many dives at Sipadan. I went to Sipadan twice, first time was with SeaVenture (the oil rig), then the second time at Borneo Diver Mabul. Each time I was in the area I only get to dive 2 days out of a 5 days trip. I wasn't overwhelmed by the diving but it could be because I was there at the wrong season or I was just not lucky since I never seen the barracuda tornado, plus I didn't have much diving experience back then.
Service standard in Asia could be a difficult subject. The Asian culture are just not friendly/chatty to strangers, especially if English is not their first language. I wonder who the owner is for the MV Celebes Explorer because if the owners is westerners, the service standard could be higher. Anyway, I will PM you since I have more questions.
This is where H.265 comes in. When Samsung release the NX1, the consensus is the consumers are not ready yet. Moving into 2016, processor on camera will improve slightly so higher frame rate compression shouldn't be a problem. If the bottleneck is the memory card, H.265 will solve it. My point is, at least Panasonic is doing something to support the technology revolution!