Hello Chaps,
I'm new here, was just searching Milliken on google and...
Anyway I use Millikens quite regularly [not sure what model off the top of my head]. They run off 28 volts, but I have never even considered underwater stuff, and dont think I would. I think I have seen one that runs 115 volts. I know of a company that sells mains transformers that will allow you to basically plug into 24o volts and convert it down to 28 volt.
I believe they can be adapted for super 16, but would be very expensive. The cameras I use require double perf standard 16mm stock [on daylight spools ]
C mount lense are generally available, including cheapo cctv lenses, but you do require some sort of viewing mechanism.
The cameras themselves need a lot of servicing, but looked after will give good service.
I may be in Central London this weekend 19th or 20th if you want some handy tips
Regards