Fish – a good fish for cooking crumbed / battered

Easy! I steam fish about 1x per week with a bamboo steamer. You need to take advantage of the steam rising from the pot which can steam your fish in exactly the same way as the rice cooker - so you get a Bamboo Steamer like this one (available in tons of different places, including cooking-supply stores, Asian Foods stores, etc): http://www.amazon.com/Norpro-Deluxe-3-Piece-Bamboo-Steamer/dp/B00005EBH8

This steamer is basically open at the bottom (with bamboo slats) so you set this on top of the boiling pot, and it fills with steam, cooking the fish. It's recommendable that you wrap the fish in wax paper (I use baking paper in a pinch) and that will keep it from sticking to the bamboo.

Hope this helps! I recommend buying a bamboo steamer like this one - it's a common kitchen item that you can use for a ton of steaming - i.e. veggies, broccoli, fish, etc. No need to even be cooking rice - you just place this over a pot of boiling water, and it works great!

That depends on how large your oven is. I certainly couldn't do 6 whole fish in mine, but then I have a 24" wide oven. If you have a 36", it would be completely possible (these are standard US sizes; no idea what the equivalent would be in other countries).

Your main adjustment will be dealing with the extra mass to be heated by the additional fish, which will cause the oven to take some additional time to reheat. Again, this depends on how hot (BTU) your oven is; a hot oven would overcome the extra mass in a few minutes, but an underpowered (for this purpose, anyway) oven might take an additional 15 or more minutes, which would not be good for the texture of the fish.

So, It Depends. If you have a fairly powerful, large, high-end stove, I'd be ready to flip them at 10 minutes. Less powerful ovens will take longer.

Also, if the fish are individually closer together than 1", you'll have the issue that the edges of each fish will be soggy from the moisture of the fish next to it, and they won't get good texture. If they're touching even slightly, they will stick together. You'll also want to try to ensure some drainage in the pan, lest all of the liquid runoff collect under one fish and make it slimy.