| snowball,
It probably doesn't matter whether you use a plastic or a wood basket. Usually wood baskets have wider spaces between the slats and so may dry out faster, but it really doesn't matter which you use.
I once heard a charming anicdote about Abraham Lincoln in which he was asked by reporter about how long a man's legs should be. Lincoln replied, "Just long enough to reach from his body to the ground." So the answer to how much potting mix should be used is, "Just enough to fill the pot." Look at how your Cattleya is potted. You'll probably notice that the mix comes up to but does not bury the rhizome of the plant. This is how it should be after you've repotted it.
Sometimes bags of orchid bark come dry and sometimes they come pre soaked. If it is dry, set it to soak overnight. When I used to get my mix dry I'd set it to soak in warm water (warm seems to work better) when I was cleaning up after dinner on Friday and it would be ready to go on Saturday morning when I started my repotting, so I guess that's about 12-18 hours.
If you don't have one, I'd recommend getting a good book on basic orchid culture. I highly recommend Ortho's All About Orchids. It's probably the best, clear and concise book I know on the basics of repotting and the various types of orchid mixes. The book is readily available in large bookstores or through amazon.com
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