I just looked over the specs for the new CoolPix. I'm not overly impressed with the L16/L18. I'm not sure how I feel about the auto ISO mode, with an external strobe that might be a bit trying and I don't think they have a video mode which you said you'd like. The s600 looks to be ok, but not out long so prices are higher at around $250.
My best recommendation is the P5100. It's been out for a while now and prices are very good for this topline camera at around $275 (BeachCamera.com). The lower priced cameras are at $160 on up and for the extra $125 you are getting a much more advanced camera, better manual features, optical stabilization, and much better lens quality.
The thing is that the housing price ($209 for Fantasea at a discount) is all the same for whatever model, so housing the best camera is the best move.
I don't know much about the Sea & Sea 860, but as per my article on my blog, most of these "underwater" cameras are simply mid-to low end Rioch or other cameras that have some special s/w, etc to give uw modes. You are much better of getting a high quality camera and housing it, be it Nikon, Canon or Olympus, etc. The electronics, lens quality and other features are much better.
The S&S YS27 is a good strobe with 8 steps of control, but for around $140 more the YS-110 is faster, has more adjustability, more powerful, has a target light and a wider beam angle and can be upgraded to DSLR hardwired sync in the future.
I know $100 here and a $140 there and pretty soon we're talking more than you can afford... But it's scuba dollars right?? ;-)
At any rate I have
Housing packages with the FP5000 housing, tray, sync cord, arms set and YS27 strobe starting at
$768. You can add in another arms, handle and focus light or upgrade to the YS110 as you like.
I am telling customers that they should order any of the S&S strobes soon, as of June 1st there will be a large price increase from S&S of 10-15% and I think Fantasea is going to see some increases as well. The strobes are about a 10 day wait right now, but I'll do my best to get them in asap. I have everything else in stock.
BTW; I do ship internationally, just sent one of these to S.A. for around $60 5-7 day Express Mail.
Jack