I'm going to Andanam Islands in 2 weeks time (via Madras).
Any practical advice would be appreciated.
I'm looking to reduce my lagguage as much as I can. What suit sould I take?
Do I need 5mm overall or 3mm shorty will be enough? I'm definitelly not skinny so I take cold quite well...
Do they use INT or DIN?
Which power plugs? Is it the same as UK ones?
We just got back from there in Feb... Diving was great although we were on the Ocean-Rover and got out to a few places even further off the beaten path.
I dove in a 2mm and my wife dove in a 3mm (both fullsuits). We both wear hooded vests though.
The water was 82-83 in Feb and even with 4 dives per day we were planty warm.
Since she gets cold pretty easily I'd say your shorty will be fine. Several divers were in shorties although one was from Canada so he doesn't count 
Can't help you on the plugs though. They have an interesting setup and we didn't have a need to charge anything until we got on the boat.
A word of advice here on luggage... they say one carry-on and sometimes they mean it.
The restriction is enforced at their security point so it is a crapshoot.
They seemed to indicate that batteries were banned but this was not enforced everywhere.
Anything that is powered and could "make a sound" seemed to be an issue as well. Fortunately they didn't realize that my dive computer could beep or that would have needed to be checked.
Never had my carryon weighed though. In fact they hardly looked askance at my large pelican when checking in. Customs was interested tho' and tried to prevent our entry because we had "too much expensive stuff". We managed to get in without paying a bribe at any rate.
Oh, and each flight transfer (like in Chennai on my Port Blair to Chennai to Mumbai leg) means another visit thru security with your carryon.
The young ticket agents are quite suseptible to a smile 