What a great line of information coming thru this topic. 123, you will get great help from these pros. I would like to address the structure materials. Your plan and list is the perfect way to start such a vigorous endevor. Try the local plumbers and building contractors for scrap pipe and wood products. We all end up with piles of cutoffs we save and never use. The lumberyard has all kinds of scrap and damaged lumber they give away. Also, all these guys can let you know when they have more. The plumbers all throw out used pvc pipe. With such a good cause, they will surely help. It can be an ongoing connection to more material.
Lastly, send me an e-mail through our site fishiding.com. We would be proud to donate some products for your project. The only catch is you have to take me fishing in a few years when you succeed!