I throw my hard wood in the dishwasher, haven't had any issues yet though one piece always funguses up every time despite my cleaning (I don't use that piece currently).
For my scaping, I allow my self to re-organize the tank if I don't like it. I have a 45 and a 10 gal that have both gone through several iterations since first getting them. Since I am continually learning, this has been instrumental. It allows me to start a project that otherwise I would procrastinate on because of being overwhelmed. I do let them sit for months, to allow plant growth, before deciding if something needs to be changed. Also, I have found that if I am not happy with the scape/tank I don't put as much effort into caring for it. So having an enjoyable setup is important for me.
TLDR; Plan it out, have fun, do it and if you don't like it in 6 month, change it up.