There are a few things you can use instead of peanuts...actually I take the sheets of styrofoam from packages and break it into chunks. It works the same. I have also used rocks, shells, as well as very large chunks of wood. Make sure and clean whatever you use first to avoid fungus. As far as pot size...you want to use one that will allow for 1-2 years of root growth. Anything too large will mean a better chance of root rot from wood holding too much water. Some orchids even prefer a smaller pot...such as dendrobiums. They like to be nice and root bound. One other thing...using rocks...I wouldn't put them in the mix unless its a small pot as they will end up weighing down the mix and not allowing for air exchange. Orchid roots will die if not allowed enough air. Unlike regular houseplants they must have air exchange or they will rot.
As far as sterilizing tools, I would suggest using bleach instead of hydrogen peroxide. I think if you do a search on the site you will find several other suggestions, including using a torch to steralize tools. I use Physan 20 as I find it works the best for me.
Good Luck and happy potting...there are a couple really good repotting articles you might want to read as I am sure they have some other great ideas i've missed.