I started with regular paper and regular size crane as well, and I guess making them smaller is more manageable than making them bigger so that's how the story goes. Not everyone finds origami easy or relaxing, but it has to be the cheapest hobby next to meditation I think :)

I don't use anything other than my own two hands, and in the case of flower petals I have to use a scalpel to cut the pressed flower petals into squares (nature doesn't produce square shaped flower petals I don't think). Here's a video of hospitals using an interesting test as part of their recruitment process (or maybe it is a marketing campaign?):

You can preserve flowers using resin, which is what I think @nature.art does with her jewellery.