Axolotls: Just a Few Questions

[Endless Ocean in My House]

I've been looking into axolotls lately and they're described as "easy" but they seem a little high maintenance to me. I had a few questions about how to meet some of their particular needs!
Temp:
Do you recommend the frozen water bottle thing? Are there any other ways to cool down the tank? (Without breaking the bank or turning your house into an igloo!)
I was planning to practice with frozen water bottles for a while until I figure out how to keep the tank at an even (and acceptable) temperature. My LFS won't get another shipment for a month or so anyway.
No Currents:
I heard that the water flow created by the output of a filter is very harmful to their gills. I looked at some different methods and I was thinking--what about one of those little strainers? I could tape it to the side of the tank and it would create more of a drizzle, less of a flow.
Bottomless VS gravel:
I read on one place that you should have a bottomless tank. I read on another that fine gravel will be ingested and you need either large and coarse gravel and that NO substrate will stress them out because they can't walk on a smooth tank bottom.

And then a superficial question: I was looking at more axolotls and it seems like there are both fleshy and dark/muddy colored varieties. Is this just like yellow/black Labrador and happens by chance if the parents are different colors?

 

[Freakgecko91]

As for the colors, there are golds, whites, and wild types. The whites i believe are true albinos while the golds are a color strain, most likely a recessive trait brought out through captive breeding. The "wild type" is that muddy brown color that you described. This is what you would find in Lake Xochimilco, in Mexico, if they weren't already at the point of near extinction